diff --git a/pkg/app/piped/analysisprovider/metrics/datadog/datadog_test.go b/pkg/app/piped/analysisprovider/metrics/datadog/datadog_test.go
index 7a5b0ed09b..9af3bfe510 100644
--- a/pkg/app/piped/analysisprovider/metrics/datadog/datadog_test.go
+++ b/pkg/app/piped/analysisprovider/metrics/datadog/datadog_test.go
@@ -29,6 +29,8 @@ import (
 )
 
 func TestProviderQueryPoints(t *testing.T) {
+	t.Parallel()
+
 	toInt64Pointer := func(i int64) *int64 { return &i }
 	type queryResponse struct {
 		res        datadog.MetricsQueryResponse
diff --git a/pkg/app/piped/analysisprovider/metrics/prometheus/prometheus_test.go b/pkg/app/piped/analysisprovider/metrics/prometheus/prometheus_test.go
index 6fba019938..b4043bb770 100644
--- a/pkg/app/piped/analysisprovider/metrics/prometheus/prometheus_test.go
+++ b/pkg/app/piped/analysisprovider/metrics/prometheus/prometheus_test.go
@@ -14,11 +14,15 @@ import (
 )
 
 func TestType(t *testing.T) {
+	t.Parallel()
+
 	p := Provider{}
 	assert.Equal(t, ProviderType, p.Type())
 }
 
 func TestProviderQueryPoints(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name       string
 		client     client
diff --git a/pkg/app/piped/apistore/analysisresultstore/BUILD.bazel b/pkg/app/piped/apistore/analysisresultstore/BUILD.bazel
index e97527520e..458f59f8b3 100644
--- a/pkg/app/piped/apistore/analysisresultstore/BUILD.bazel
+++ b/pkg/app/piped/apistore/analysisresultstore/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -14,10 +14,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["store_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/apistore/analysisresultstore/store_test.go b/pkg/app/piped/apistore/analysisresultstore/store_test.go
deleted file mode 100644
index ca5d6fcd75..0000000000
--- a/pkg/app/piped/apistore/analysisresultstore/store_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2021 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package analysisresultstore
diff --git a/pkg/app/piped/apistore/applicationstore/BUILD.bazel b/pkg/app/piped/apistore/applicationstore/BUILD.bazel
index bc088754b7..f0c4ae3fa5 100644
--- a/pkg/app/piped/apistore/applicationstore/BUILD.bazel
+++ b/pkg/app/piped/apistore/applicationstore/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -12,10 +12,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["store_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/apistore/applicationstore/store_test.go b/pkg/app/piped/apistore/applicationstore/store_test.go
deleted file mode 100644
index 69ffa9c9a3..0000000000
--- a/pkg/app/piped/apistore/applicationstore/store_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package applicationstore
diff --git a/pkg/app/piped/apistore/commandstore/BUILD.bazel b/pkg/app/piped/apistore/commandstore/BUILD.bazel
index f34b15e543..ab9f9ef0f6 100644
--- a/pkg/app/piped/apistore/commandstore/BUILD.bazel
+++ b/pkg/app/piped/apistore/commandstore/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -12,10 +12,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["store_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/apistore/commandstore/store_test.go b/pkg/app/piped/apistore/commandstore/store_test.go
deleted file mode 100644
index 7d94152e36..0000000000
--- a/pkg/app/piped/apistore/commandstore/store_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package commandstore
diff --git a/pkg/app/piped/apistore/deploymentstore/BUILD.bazel b/pkg/app/piped/apistore/deploymentstore/BUILD.bazel
index c26a131594..83df5e22e6 100644
--- a/pkg/app/piped/apistore/deploymentstore/BUILD.bazel
+++ b/pkg/app/piped/apistore/deploymentstore/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -12,10 +12,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["store_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/apistore/deploymentstore/store_test.go b/pkg/app/piped/apistore/deploymentstore/store_test.go
deleted file mode 100644
index 815aa6b41c..0000000000
--- a/pkg/app/piped/apistore/deploymentstore/store_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package deploymentstore
diff --git a/pkg/app/piped/apistore/eventstore/BUILD.bazel b/pkg/app/piped/apistore/eventstore/BUILD.bazel
index f6fd625f5b..ae609b2469 100644
--- a/pkg/app/piped/apistore/eventstore/BUILD.bazel
+++ b/pkg/app/piped/apistore/eventstore/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -12,10 +12,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["store_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/apistore/eventstore/store_test.go b/pkg/app/piped/apistore/eventstore/store_test.go
deleted file mode 100644
index 3231b0741e..0000000000
--- a/pkg/app/piped/apistore/eventstore/store_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2021 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package eventstore
diff --git a/pkg/app/piped/appconfigreporter/appconfigreporter_test.go b/pkg/app/piped/appconfigreporter/appconfigreporter_test.go
index e1bd4989c1..210ba06959 100644
--- a/pkg/app/piped/appconfigreporter/appconfigreporter_test.go
+++ b/pkg/app/piped/appconfigreporter/appconfigreporter_test.go
@@ -34,6 +34,8 @@ func (f *fakeApplicationLister) List() []*model.Application {
 }
 
 func TestReporter_findRegisteredApps(t *testing.T) {
+	t.Parallel()
+
 	type args struct {
 		repoPath string
 		repoID   string
@@ -162,6 +164,8 @@ spec:
 }
 
 func TestReporter_findUnregisteredApps(t *testing.T) {
+	t.Parallel()
+
 	type args struct {
 		registeredAppPaths map[string]string
 		repoPath, repoID   string
diff --git a/pkg/app/piped/cloudprovider/cloudrun/client_test.go b/pkg/app/piped/cloudprovider/cloudrun/client_test.go
index 75de34e6c7..2b936d102c 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/client_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/client_test.go
@@ -21,6 +21,8 @@ import (
 )
 
 func TestMakeCloudRunParent(t *testing.T) {
+	t.Parallel()
+
 	const projectID = "projectID"
 	got := makeCloudRunParent(projectID)
 	want := "namespaces/projectID"
@@ -28,6 +30,8 @@ func TestMakeCloudRunParent(t *testing.T) {
 }
 
 func TestMakeCloudRunServiceName(t *testing.T) {
+	t.Parallel()
+
 	const (
 		projectID = "projectID"
 		serviceID = "serviceID"
@@ -38,6 +42,8 @@ func TestMakeCloudRunServiceName(t *testing.T) {
 }
 
 func TestMakeCloudRunRevisionName(t *testing.T) {
+	t.Parallel()
+
 	const (
 		projectID  = "projectID"
 		revisionID = "revisionID"
diff --git a/pkg/app/piped/cloudprovider/cloudrun/cloudrun_test.go b/pkg/app/piped/cloudprovider/cloudrun/cloudrun_test.go
index 82136f8c38..d1e10f6cd9 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/cloudrun_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/cloudrun_test.go
@@ -24,6 +24,8 @@ import (
 )
 
 func TestLoadServiceManifest(t *testing.T) {
+	t.Parallel()
+
 	const (
 		appDir      = "testdata"
 		serviceFile = "new_manifest.yaml"
@@ -39,12 +41,16 @@ func TestLoadServiceManifest(t *testing.T) {
 }
 
 func TestMakeManagedByPipedSelector(t *testing.T) {
+	t.Parallel()
+
 	want := "pipecd-dev-managed-by=piped"
 	got := MakeManagedByPipedSelector()
 	assert.Equal(t, want, got)
 }
 
 func TestMakeRevisionNamesSelector(t *testing.T) {
+	t.Parallel()
+
 	names := []string{"test-1", "test-2", "test-3"}
 	got := MakeRevisionNamesSelector(names)
 	want := "pipecd-dev-revision-name in (test-1,test-2,test-3)"
@@ -52,6 +58,8 @@ func TestMakeRevisionNamesSelector(t *testing.T) {
 }
 
 func TestService(t *testing.T) {
+	t.Parallel()
+
 	sm, err := ParseServiceManifest([]byte(serviceManifest))
 	require.NoError(t, err)
 
@@ -75,6 +83,8 @@ func TestService(t *testing.T) {
 }
 
 func TestService_HealthStatus(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		manifest string
@@ -309,6 +319,8 @@ status:
 }
 
 func TestRevision(t *testing.T) {
+	t.Parallel()
+
 	rm, err := ParseRevisionManifest([]byte(revisionManifest))
 	require.NoError(t, err)
 	require.NotEmpty(t, rm)
@@ -323,6 +335,8 @@ func TestRevision(t *testing.T) {
 }
 
 func TestRevision_HealthStatus(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		manifest string
diff --git a/pkg/app/piped/cloudprovider/cloudrun/diff_test.go b/pkg/app/piped/cloudprovider/cloudrun/diff_test.go
index 72d1e60eed..f95ae25ec1 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/diff_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/diff_test.go
@@ -22,6 +22,8 @@ import (
 )
 
 func TestDiff(t *testing.T) {
+	t.Parallel()
+
 	old, err := loadServiceManifest("testdata/old_manifest.yaml")
 	require.NoError(t, err)
 	require.NotEmpty(t, old)
@@ -42,6 +44,8 @@ func TestDiff(t *testing.T) {
 }
 
 func TestDiffResult_NoChange(t *testing.T) {
+	t.Parallel()
+
 	old, err := loadServiceManifest("testdata/old_manifest.yaml")
 	require.NoError(t, err)
 	require.NotEmpty(t, old)
@@ -100,6 +104,8 @@ func TestDiffResult_Render(t *testing.T) {
 }
 
 func TestDiffByCommand(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name        string
 		command     string
diff --git a/pkg/app/piped/cloudprovider/cloudrun/revisionmanifest_test.go b/pkg/app/piped/cloudprovider/cloudrun/revisionmanifest_test.go
index 3dbb021ac6..c6e2ae5fb9 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/revisionmanifest_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/revisionmanifest_test.go
@@ -86,6 +86,8 @@ status:
 `
 
 func TestRevisionManifest(t *testing.T) {
+	t.Parallel()
+
 	rm, err := ParseRevisionManifest([]byte(revisionManifest))
 	require.NoError(t, err)
 	require.NotEmpty(t, rm)
diff --git a/pkg/app/piped/cloudprovider/cloudrun/servicemanifest_test.go b/pkg/app/piped/cloudprovider/cloudrun/servicemanifest_test.go
index 7818155f78..e8135dc50d 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/servicemanifest_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/servicemanifest_test.go
@@ -82,6 +82,8 @@ status:
 `
 
 func TestServiceManifest(t *testing.T) {
+	t.Parallel()
+
 	sm, err := ParseServiceManifest([]byte(serviceManifest))
 	require.NoError(t, err)
 	require.NotEmpty(t, sm)
@@ -143,6 +145,8 @@ func TestServiceManifest(t *testing.T) {
 }
 
 func TestParseServiceManifest(t *testing.T) {
+	t.Parallel()
+
 	// Success
 	data := []byte(serviceManifest)
 	sm, err := ParseServiceManifest(data)
@@ -156,6 +160,8 @@ func TestParseServiceManifest(t *testing.T) {
 }
 
 func TestDecideRevisionName(t *testing.T) {
+	t.Parallel()
+
 	data := []byte(serviceManifest)
 	sm, err := ParseServiceManifest(data)
 	require.NoError(t, err)
@@ -166,6 +172,8 @@ func TestDecideRevisionName(t *testing.T) {
 }
 
 func TestFindImageTag(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		manifest string
diff --git a/pkg/app/piped/cloudprovider/cloudrun/state_test.go b/pkg/app/piped/cloudprovider/cloudrun/state_test.go
index 24213045e8..7bdda1b33c 100644
--- a/pkg/app/piped/cloudprovider/cloudrun/state_test.go
+++ b/pkg/app/piped/cloudprovider/cloudrun/state_test.go
@@ -25,6 +25,8 @@ import (
 )
 
 func TestMakeResourceStates(t *testing.T) {
+	t.Parallel()
+
 	sm, err := ParseServiceManifest([]byte(serviceManifest))
 	require.NoError(t, err)
 
diff --git a/pkg/app/piped/cloudprovider/ecs/servce_test.go b/pkg/app/piped/cloudprovider/ecs/servce_test.go
index a76f24fab9..c400f66984 100644
--- a/pkg/app/piped/cloudprovider/ecs/servce_test.go
+++ b/pkg/app/piped/cloudprovider/ecs/servce_test.go
@@ -23,6 +23,8 @@ import (
 )
 
 func TestParseServiceDefinition(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name        string
 		input       string
diff --git a/pkg/app/piped/cloudprovider/ecs/task_test.go b/pkg/app/piped/cloudprovider/ecs/task_test.go
index 78f6dc1ee9..979b717641 100644
--- a/pkg/app/piped/cloudprovider/ecs/task_test.go
+++ b/pkg/app/piped/cloudprovider/ecs/task_test.go
@@ -23,6 +23,8 @@ import (
 )
 
 func TestParseTaskDefinition(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name        string
 		input       string
diff --git a/pkg/app/piped/cloudprovider/kubernetes/deployment_test.go b/pkg/app/piped/cloudprovider/kubernetes/deployment_test.go
index 825c958b0f..8a6faa18e2 100644
--- a/pkg/app/piped/cloudprovider/kubernetes/deployment_test.go
+++ b/pkg/app/piped/cloudprovider/kubernetes/deployment_test.go
@@ -24,6 +24,8 @@ import (
 )
 
 func TestFindReferencingConfigMapsInDeployment(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		manifest string
@@ -189,6 +191,8 @@ spec:
 }
 
 func TestFindReferencingSecretsInDeployment(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		manifest string
diff --git a/pkg/app/piped/cloudprovider/kubernetes/diff_test.go b/pkg/app/piped/cloudprovider/kubernetes/diff_test.go
index db4943e812..9d09529197 100644
--- a/pkg/app/piped/cloudprovider/kubernetes/diff_test.go
+++ b/pkg/app/piped/cloudprovider/kubernetes/diff_test.go
@@ -24,6 +24,8 @@ import (
 )
 
 func TestGroupManifests(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name               string
 		olds               []Manifest
@@ -118,6 +120,8 @@ func TestGroupManifests(t *testing.T) {
 }
 
 func TestDiffByCommand(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name        string
 		command     string
@@ -188,6 +192,8 @@ func TestDiffByCommand(t *testing.T) {
 }
 
 func TestDiff(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
diff --git a/pkg/app/piped/cloudprovider/kubernetes/hasher_test.go b/pkg/app/piped/cloudprovider/kubernetes/hasher_test.go
index ed49262818..0589da5c80 100644
--- a/pkg/app/piped/cloudprovider/kubernetes/hasher_test.go
+++ b/pkg/app/piped/cloudprovider/kubernetes/hasher_test.go
@@ -23,6 +23,8 @@ import (
 )
 
 func TestHashManifests(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
diff --git a/pkg/app/piped/cloudprovider/kubernetes/helm_test.go b/pkg/app/piped/cloudprovider/kubernetes/helm_test.go
index fb20af3db1..18ef3db08e 100644
--- a/pkg/app/piped/cloudprovider/kubernetes/helm_test.go
+++ b/pkg/app/piped/cloudprovider/kubernetes/helm_test.go
@@ -27,6 +27,8 @@ import (
 )
 
 func TestTemplateLocalChart(t *testing.T) {
+	t.Parallel()
+
 	var (
 		ctx       = context.Background()
 		appName   = "testapp"
@@ -48,6 +50,8 @@ func TestTemplateLocalChart(t *testing.T) {
 }
 
 func TestTemplateLocalChart_WithNamespace(t *testing.T) {
+	t.Parallel()
+
 	var (
 		ctx       = context.Background()
 		appName   = "testapp"
diff --git a/pkg/app/piped/cloudprovider/kubernetes/kustomize_test.go b/pkg/app/piped/cloudprovider/kubernetes/kustomize_test.go
index 467858da04..74e5d642ae 100644
--- a/pkg/app/piped/cloudprovider/kubernetes/kustomize_test.go
+++ b/pkg/app/piped/cloudprovider/kubernetes/kustomize_test.go
@@ -26,6 +26,8 @@ import (
 )
 
 func TestKustomizeTemplate(t *testing.T) {
+	t.Parallel()
+
 	var (
 		ctx     = context.TODO()
 		appName = "testapp"
diff --git a/pkg/app/piped/cloudprovider/lambda/client_test.go b/pkg/app/piped/cloudprovider/lambda/client_test.go
index 6634217e91..1e25447c4d 100644
--- a/pkg/app/piped/cloudprovider/lambda/client_test.go
+++ b/pkg/app/piped/cloudprovider/lambda/client_test.go
@@ -21,6 +21,8 @@ import (
 )
 
 func TestMakeFlowControlTagsMap(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name                 string
 		remoteTags           map[string]string
diff --git a/pkg/app/piped/cloudprovider/lambda/function_test.go b/pkg/app/piped/cloudprovider/lambda/function_test.go
index ac7126204b..2805e8c54a 100644
--- a/pkg/app/piped/cloudprovider/lambda/function_test.go
+++ b/pkg/app/piped/cloudprovider/lambda/function_test.go
@@ -21,6 +21,8 @@ import (
 )
 
 func TestparseFunctionManifest(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name     string
 		data     string
diff --git a/pkg/app/piped/cloudprovider/terraform/BUILD.bazel b/pkg/app/piped/cloudprovider/terraform/BUILD.bazel
index 083c581140..c0e4339dbc 100644
--- a/pkg/app/piped/cloudprovider/terraform/BUILD.bazel
+++ b/pkg/app/piped/cloudprovider/terraform/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -6,10 +6,3 @@ go_library(
     importpath = "github.com/pipe-cd/pipecd/pkg/app/piped/cloudprovider/terraform",
     visibility = ["//visibility:public"],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["terraform_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/cloudprovider/terraform/terraform_test.go b/pkg/app/piped/cloudprovider/terraform/terraform_test.go
deleted file mode 100644
index b2dcb81a31..0000000000
--- a/pkg/app/piped/cloudprovider/terraform/terraform_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package terraform
diff --git a/pkg/app/piped/controller/BUILD.bazel b/pkg/app/piped/controller/BUILD.bazel
index 03b52fc43f..5496b55a13 100644
--- a/pkg/app/piped/controller/BUILD.bazel
+++ b/pkg/app/piped/controller/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -31,10 +31,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["controller_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/controller/controller_test.go b/pkg/app/piped/controller/controller_test.go
deleted file mode 100644
index 13eac88c63..0000000000
--- a/pkg/app/piped/controller/controller_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package controller
diff --git a/pkg/app/piped/deploysource/BUILD.bazel b/pkg/app/piped/deploysource/BUILD.bazel
index 84daf1a3bb..2ae9cbec62 100644
--- a/pkg/app/piped/deploysource/BUILD.bazel
+++ b/pkg/app/piped/deploysource/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -15,10 +15,3 @@ go_library(
         "//pkg/model:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["deploysource_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/deploysource/deploysource_test.go b/pkg/app/piped/deploysource/deploysource_test.go
deleted file mode 100644
index 7fca4871cf..0000000000
--- a/pkg/app/piped/deploysource/deploysource_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package deploysource
diff --git a/pkg/app/piped/eventwatcher/eventwatcher_test.go b/pkg/app/piped/eventwatcher/eventwatcher_test.go
index 47d887cc19..2e45840dc8 100644
--- a/pkg/app/piped/eventwatcher/eventwatcher_test.go
+++ b/pkg/app/piped/eventwatcher/eventwatcher_test.go
@@ -21,6 +21,8 @@ import (
 )
 
 func TestConvertStr(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name    string
 		value   interface{}
@@ -80,6 +82,8 @@ func TestConvertStr(t *testing.T) {
 }
 
 func TestModifyYAML(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name         string
 		path         string
@@ -119,6 +123,8 @@ func TestModifyYAML(t *testing.T) {
 }
 
 func TestModifyText(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name         string
 		path         string
diff --git a/pkg/app/piped/executor/analysis/mannwhitney/mannwhitney_test.go b/pkg/app/piped/executor/analysis/mannwhitney/mannwhitney_test.go
index 6a63ecae71..5d23919504 100644
--- a/pkg/app/piped/executor/analysis/mannwhitney/mannwhitney_test.go
+++ b/pkg/app/piped/executor/analysis/mannwhitney/mannwhitney_test.go
@@ -21,11 +21,13 @@ package mannwhitney
 import "testing"
 
 func TestMannWhitneyUTest(t *testing.T) {
+	t.Parallel()
+
 	check := func(want, got *MannWhitneyUTestResult) {
 		if want.N1 != got.N1 || want.N2 != got.N2 ||
-			!aeq(want.U, got.U) ||
+			!aeq(t, want.U, got.U) ||
 			want.AltHypothesis != got.AltHypothesis ||
-			!aeq(want.P, got.P) {
+			!aeq(t, want.P, got.P) {
 			t.Errorf("want %+v, got %+v", want, got)
 		}
 	}
diff --git a/pkg/app/piped/executor/analysis/mannwhitney/udist_test.go b/pkg/app/piped/executor/analysis/mannwhitney/udist_test.go
index a74bae4b1b..b5558f19fa 100644
--- a/pkg/app/piped/executor/analysis/mannwhitney/udist_test.go
+++ b/pkg/app/piped/executor/analysis/mannwhitney/udist_test.go
@@ -24,7 +24,9 @@ import (
 	"testing"
 )
 
-func aeqTable(a, b [][]float64) bool {
+func aeqTable(t *testing.T, a, b [][]float64) bool {
+	t.Helper()
+
 	if len(a) != len(b) {
 		return false
 	}
@@ -65,6 +67,8 @@ var udist5 = [][]float64{
 }
 
 func TestUDist(t *testing.T) {
+	t.Parallel()
+
 	makeTable := func(n int) [][]float64 {
 		out := make([][]float64, 6)
 		for U := 0; U < 6; U++ {
@@ -94,12 +98,12 @@ func TestUDist(t *testing.T) {
 
 	// Compare against tables given in Mann, Whitney (1947).
 	got3 := makeTable(3)
-	if !aeqTable(got3, udist3) {
+	if !aeqTable(t, got3, udist3) {
 		t.Errorf("For n=3, want:\n%sgot:\n%s", fmtTable(udist3), fmtTable(got3))
 	}
 
 	got5 := makeTable(5)
-	if !aeqTable(got5, udist5) {
+	if !aeqTable(t, got5, udist5) {
 		t.Errorf("For n=5, want:\n%sgot:\n%s", fmtTable(udist5), fmtTable(got5))
 	}
 }
@@ -113,14 +117,16 @@ func BenchmarkUDist(b *testing.B) {
 }
 
 func TestUDistTies(t *testing.T) {
-	makeTable := func(m, N int, t []int, minx, maxx float64) [][]float64 {
+	t.Parallel()
+
+	makeTable := func(m, N int, tVar []int, minx, maxx float64) [][]float64 {
 		out := [][]float64{}
-		dist := UDist{N1: m, N2: N - m, T: t}
+		dist := UDist{N1: m, N2: N - m, T: tVar}
 		for x := minx; x <= maxx; x += 0.5 {
 			// Convert x from uQt' to uQv'.
 			U := x - float64(m*m)/2
 			P := dist.CDF(U)
-			if len(out) == 0 || !aeq(out[len(out)-1][1], P) {
+			if len(out) == 0 || !aeq(t, out[len(out)-1][1], P) {
 				out = append(out, []float64{x, P})
 			}
 		}
@@ -142,7 +148,7 @@ func TestUDistTies(t *testing.T) {
 		{17.5, 0.071429}, {18.0, 0.087302},
 		{19.0, 0.134921}, {19.5, 0.138889},
 	}
-	if !aeqTable(got, want) {
+	if !aeqTable(t, got, want) {
 		t.Errorf("Want:\n%sgot:\n%s", fmtTable(want), fmtTable(got))
 	}
 
@@ -175,7 +181,7 @@ func TestUDistTies(t *testing.T) {
 		{85.5, 0.083498}, {86.0, 0.094079},
 		{86.5, 0.096693}, {87.0, 0.101132},
 	}
-	if !aeqTable(got, want) {
+	if !aeqTable(t, got, want) {
 		t.Errorf("Want:\n%sgot:\n%s", fmtTable(want), fmtTable(got))
 	}
 
@@ -188,14 +194,14 @@ func TestUDistTies(t *testing.T) {
 		{48.0, 0.057187}, {50.0, 0.086713},
 		{52.0, 0.126263}, {54.0, 0.175369},
 	}
-	if !aeqTable(got, want) {
+	if !aeqTable(t, got, want) {
 		t.Errorf("Want:\n%sgot:\n%s", fmtTable(want), fmtTable(got))
 	}
 
 	// Check remaining tables from Klotz against the reference
 	// implementation.
 	checkRef := func(n1 int, tie []int) {
-		wantPMF1, wantCDF1 := udistRef(n1, tie)
+		wantPMF1, wantCDF1 := udistRef(t, n1, tie)
 
 		dist := UDist{N1: n1, N2: sumint(tie) - n1, T: tie}
 		gotPMF, wantPMF := [][]float64{}, [][]float64{}
@@ -207,10 +213,10 @@ func TestUDistTies(t *testing.T) {
 			wantPMF = append(wantPMF, []float64{U, wantPMF1[int(U*2)]})
 			wantCDF = append(wantCDF, []float64{U, wantCDF1[int(U*2)]})
 		}
-		if !aeqTable(wantPMF, gotPMF) {
+		if !aeqTable(t, wantPMF, gotPMF) {
 			t.Errorf("For PMF of n1=%v, t=%v, want:\n%sgot:\n%s", n1, tie, fmtTable(wantPMF), fmtTable(gotPMF))
 		}
-		if !aeqTable(wantCDF, gotCDF) {
+		if !aeqTable(t, wantCDF, gotCDF) {
 			t.Errorf("For CDF of n1=%v, t=%v, want:\n%sgot:\n%s", n1, tie, fmtTable(wantCDF), fmtTable(gotCDF))
 		}
 	}
@@ -239,7 +245,7 @@ func BenchmarkUDistTies(b *testing.B) {
 func XTestPrintUmemo(t *testing.T) {
 	// Reproduce table from Cheung, Klotz.
 	ties := []int{4, 5, 3, 4, 6}
-	printUmemo(makeUmemo(80, 10, ties), ties)
+	printUmemo(t, makeUmemo(80, 10, ties), ties)
 }
 
 // udistRef computes the PMF and CDF of the U distribution for two
@@ -249,20 +255,21 @@ func XTestPrintUmemo(t *testing.T) {
 // This uses the "graphical method" of Klotz (1966). It is very slow
 // (Θ(∏ (t[i]+1)) = Ω(2^|t|)), but very correct, and hence useful as a
 // reference for testing faster implementations.
-func udistRef(n1 int, t []int) (pmf, cdf []float64) {
-	// Enumerate all u vectors for which 0 <= u_i <= t_i. Count
+func udistRef(t *testing.T, n1 int, tVar []int) (pmf, cdf []float64) {
+	t.Helper()
+	// Enumerate all u vectors for which 0 <= ui <= tVari. Count
 	// the number of permutations of two samples of sizes n1 and
 	// sum(t)-n1 with tie vector t and accumulate these counts by
 	// their U statistics in count[2*U].
-	counts := make([]int, 1+2*n1*(sumint(t)-n1))
+	counts := make([]int, 1+2*n1*(sumint(tVar)-n1))
 
-	u := make([]int, len(t))
+	u := make([]int, len(tVar))
 	u[0] = -1 // Get enumeration started.
 enumu:
 	for {
 		// Compute the next u vector.
 		u[0]++
-		for i := 0; i < len(u) && u[i] > t[i]; i++ {
+		for i := 0; i < len(u) && u[i] > tVar[i]; i++ {
 			if i == len(u)-1 {
 				// All u vectors have been enumerated.
 				break enumu
@@ -282,18 +289,18 @@ enumu:
 
 		// Compute 2*U statistic for this u vector.
 		twoU, vsum := 0, 0
-		for i, u_i := range u {
-			v_i := t[i] - u_i
-			// U = U + vsum*u_i + u_i*v_i/2
-			twoU += 2*vsum*u_i + u_i*v_i
-			vsum += v_i
+		for i, ui := range u {
+			vi := tVar[i] - ui
+			// U = U + vsum*ui + ui*vi/2
+			twoU += 2*vsum*ui + ui*vi
+			vsum += vi
 		}
 
-		// Compute Π choose(t_i, u_i). This is the number of
+		// Compute Π choose(tVari, ui). This is the number of
 		// ways of permuting the input sample under u.
 		prod := 1
-		for i, u_i := range u {
-			prod *= int(mathChoose(t[i], u_i) + 0.5)
+		for i, ui := range u {
+			prod *= int(mathChoose(tVar[i], ui) + 0.5)
 		}
 
 		// Accumulate the permutations on this u path.
@@ -313,7 +320,7 @@ enumu:
 	// Convert counts into probabilities for PMF and CDF.
 	pmf = make([]float64, len(counts))
 	cdf = make([]float64, len(counts))
-	total := int(mathChoose(sumint(t), n1) + 0.5)
+	total := int(mathChoose(sumint(tVar), n1) + 0.5)
 	for i, count := range counts {
 		pmf[i] = float64(count) / float64(total)
 		if i > 0 {
@@ -325,11 +332,13 @@ enumu:
 }
 
 // printUmemo prints the output of makeUmemo for debugging.
-func printUmemo(A []map[ukey]float64, t []int) {
+func printUmemo(t *testing.T, A []map[ukey]float64, tVar []int) {
+	t.Helper()
+
 	fmt.Printf("K\tn1\t2*U\tpr\n")
 	for K := len(A) - 1; K >= 0; K-- {
 		for i, pr := range A[K] {
-			_, ref := udistRef(i.n1, t[:K])
+			_, ref := udistRef(t, i.n1, tVar[:K])
 			fmt.Printf("%v\t%v\t%v\t%v\t%v\n", K, i.n1, i.twoU, pr, ref[i.twoU])
 		}
 	}
diff --git a/pkg/app/piped/executor/analysis/mannwhitney/util_test.go b/pkg/app/piped/executor/analysis/mannwhitney/util_test.go
index a4f6a8ce96..c1411e8ddb 100644
--- a/pkg/app/piped/executor/analysis/mannwhitney/util_test.go
+++ b/pkg/app/piped/executor/analysis/mannwhitney/util_test.go
@@ -27,6 +27,8 @@ import (
 )
 
 func testDiscreteCDF(t *testing.T, name string, dist DiscreteDist) {
+	t.Parallel()
+
 	// Build the expected CDF out of the PMF.
 	l, h := dist.Bounds()
 	s := dist.Step()
@@ -42,6 +44,8 @@ func testDiscreteCDF(t *testing.T, name string, dist DiscreteDist) {
 }
 
 func testInvCDF(t *testing.T, dist Dist, bounded bool) {
+	t.Parallel()
+
 	inv := InvCDF(dist)
 	name := fmt.Sprintf("InvCDF(%+v)", dist)
 	cdfName := fmt.Sprintf("CDF(%+v)", dist)
@@ -71,7 +75,7 @@ func testInvCDF(t *testing.T, dist Dist, bounded bool) {
 
 	// Test points between.
 	vals = map[float64]float64{}
-	for _, p := range vecLinspace(0, 1, 11) {
+	for _, p := range vecLinspace(t, 0, 1, 11) {
 		if p == 0 || p == 1 {
 			continue
 		}
@@ -87,7 +91,9 @@ func testInvCDF(t *testing.T, dist Dist, bounded bool) {
 
 // aeq returns true if expect and got are equal to 8 significant
 // figures (1 part in 100 million).
-func aeq(expect, got float64) bool {
+func aeq(t *testing.T, expect, got float64) bool {
+	t.Helper()
+
 	if expect < 0 && got < 0 {
 		expect, got = -expect, -got
 	}
@@ -95,6 +101,8 @@ func aeq(expect, got float64) bool {
 }
 
 func testFunc(t *testing.T, name string, f func(float64) float64, vals map[float64]float64) {
+	t.Parallel()
+
 	xs := make([]float64, 0, len(vals))
 	for x := range vals {
 		xs = append(xs, x)
@@ -103,7 +111,7 @@ func testFunc(t *testing.T, name string, f func(float64) float64, vals map[float
 
 	for _, x := range xs {
 		want, got := vals[x], f(x)
-		if math.IsNaN(want) && math.IsNaN(got) || aeq(want, got) {
+		if math.IsNaN(want) && math.IsNaN(got) || aeq(t, want, got) {
 			continue
 		}
 		var label string
@@ -118,7 +126,9 @@ func testFunc(t *testing.T, name string, f func(float64) float64, vals map[float
 
 // vecLinspace returns num values spaced evenly between lo and hi,
 // inclusive. If num is 1, this returns an array consisting of lo.
-func vecLinspace(lo, hi float64, num int) []float64 {
+func vecLinspace(t *testing.T, lo, hi float64, num int) []float64 {
+	t.Helper()
+
 	res := make([]float64, num)
 	if num == 1 {
 		res[0] = lo
diff --git a/pkg/app/piped/executor/analysis/metrics_analyzer_test.go b/pkg/app/piped/executor/analysis/metrics_analyzer_test.go
index af61042ab3..48dcd6890f 100644
--- a/pkg/app/piped/executor/analysis/metrics_analyzer_test.go
+++ b/pkg/app/piped/executor/analysis/metrics_analyzer_test.go
@@ -49,6 +49,8 @@ func (l *fakeLogPersister) Errorf(_ string, _ ...interface{})   {}
 func floatToPointer(n float64) *float64 { return &n }
 
 func Test_metricsAnalyzer_analyzeWithThreshold(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name            string
 		metricsAnalyzer *metricsAnalyzer
@@ -137,6 +139,8 @@ func Test_metricsAnalyzer_analyzeWithThreshold(t *testing.T) {
 }
 
 func Test_compare(t *testing.T) {
+	t.Parallel()
+
 	type args struct {
 		experiment []float64
 		control    []float64
@@ -229,6 +233,8 @@ func Test_compare(t *testing.T) {
 }
 
 func Test_metricsAnalyzer_renderQuery(t *testing.T) {
+	t.Parallel()
+
 	type args struct {
 		queryTemplate     string
 		variantCustomArgs map[string]string
diff --git a/pkg/app/piped/executor/cloudrun/cloudrun_test.go b/pkg/app/piped/executor/cloudrun/cloudrun_test.go
index 1811862c54..fb284683cb 100644
--- a/pkg/app/piped/executor/cloudrun/cloudrun_test.go
+++ b/pkg/app/piped/executor/cloudrun/cloudrun_test.go
@@ -58,6 +58,8 @@ spec:
 `
 
 func TestAddBuiltinLabels(t *testing.T) {
+	t.Parallel()
+
 	var (
 		hash         = "commit-hash"
 		pipedID      = "piped-id"
diff --git a/pkg/app/piped/executor/kubernetes/canary_test.go b/pkg/app/piped/executor/kubernetes/canary_test.go
index 69e15e8cc3..9c45178804 100644
--- a/pkg/app/piped/executor/kubernetes/canary_test.go
+++ b/pkg/app/piped/executor/kubernetes/canary_test.go
@@ -34,6 +34,8 @@ import (
 )
 
 func TestEnsureCanaryRollout(t *testing.T) {
+	t.Parallel()
+
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 
diff --git a/pkg/app/piped/executor/kubernetes/kubernetes_test.go b/pkg/app/piped/executor/kubernetes/kubernetes_test.go
index cc84d8e7b2..344b62b64c 100644
--- a/pkg/app/piped/executor/kubernetes/kubernetes_test.go
+++ b/pkg/app/piped/executor/kubernetes/kubernetes_test.go
@@ -63,6 +63,8 @@ func (m *fakeMetadataStageStore) Put(_ context.Context, _, _ string) error
 func (m *fakeMetadataStageStore) PutMulti(_ context.Context, _ map[string]string) error { return nil }
 
 func TestGenerateServiceManifests(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifestsFile string
@@ -88,6 +90,8 @@ func TestGenerateServiceManifests(t *testing.T) {
 }
 
 func TestGenerateVariantWorkloadManifests(t *testing.T) {
+	t.Parallel()
+
 	const (
 		variantLabel  = "pipecd.dev/variant"
 		canaryVariant = "canary-variant"
@@ -146,6 +150,8 @@ func TestGenerateVariantWorkloadManifests(t *testing.T) {
 }
 
 func TestCheckVariantSelectorInWorkload(t *testing.T) {
+	t.Parallel()
+
 	const (
 		variantLabel   = "pipecd.dev/variant"
 		primaryVariant = "primary"
@@ -291,6 +297,8 @@ spec:
 }
 
 func TestApplyManifests(t *testing.T) {
+	t.Parallel()
+
 	ctrl := gomock.NewController(t)
 
 	testcases := []struct {
@@ -469,6 +477,8 @@ spec:
 }
 
 func TestDeleteResources(t *testing.T) {
+	t.Parallel()
+
 	ctrl := gomock.NewController(t)
 
 	testcases := []struct {
@@ -535,6 +545,8 @@ func TestDeleteResources(t *testing.T) {
 }
 
 func TestAnnotateConfigHash(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
@@ -768,6 +780,8 @@ data:
 }
 
 func TestPatchManifest(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
@@ -877,6 +891,8 @@ func TestPatchManifest(t *testing.T) {
 }
 
 func TestPatchManifests(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name        string
 		input       []provider.Manifest
diff --git a/pkg/app/piped/executor/kubernetes/primary_test.go b/pkg/app/piped/executor/kubernetes/primary_test.go
index dc1f598347..d2955b170d 100644
--- a/pkg/app/piped/executor/kubernetes/primary_test.go
+++ b/pkg/app/piped/executor/kubernetes/primary_test.go
@@ -34,6 +34,8 @@ import (
 )
 
 func TestEnsurePrimaryRollout(t *testing.T) {
+	t.Parallel()
+
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 
@@ -296,6 +298,7 @@ func TestEnsurePrimaryRollout(t *testing.T) {
 	}
 	for _, tc := range testcases {
 		t.Run(tc.name, func(t *testing.T) {
+
 			ctx := context.Background()
 			got := tc.executor.ensurePrimaryRollout(ctx)
 			assert.Equal(t, tc.want, got)
@@ -304,6 +307,8 @@ func TestEnsurePrimaryRollout(t *testing.T) {
 }
 
 func TestFindRemoveManifests(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name      string
 		prevs     []provider.Manifest
diff --git a/pkg/app/piped/executor/kubernetes/sync_test.go b/pkg/app/piped/executor/kubernetes/sync_test.go
index 28d39c1e20..465f81d5df 100644
--- a/pkg/app/piped/executor/kubernetes/sync_test.go
+++ b/pkg/app/piped/executor/kubernetes/sync_test.go
@@ -34,6 +34,8 @@ import (
 )
 
 func TestEnsureSync(t *testing.T) {
+	t.Parallel()
+
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 
@@ -159,6 +161,8 @@ func TestEnsureSync(t *testing.T) {
 }
 
 func TestFindRemoveResources(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     []provider.Manifest
diff --git a/pkg/app/piped/executor/kubernetes/traffic_test.go b/pkg/app/piped/executor/kubernetes/traffic_test.go
index f30964877f..5851f0a47c 100644
--- a/pkg/app/piped/executor/kubernetes/traffic_test.go
+++ b/pkg/app/piped/executor/kubernetes/traffic_test.go
@@ -26,6 +26,8 @@ import (
 )
 
 func TestGenerateVirtualServiceManifest(t *testing.T) {
+	t.Parallel()
+
 	exec := &deployExecutor{
 		appCfg: &config.KubernetesApplicationSpec{
 			VariantLabel: config.KubernetesVariantLabel{
@@ -78,6 +80,8 @@ func TestGenerateVirtualServiceManifest(t *testing.T) {
 }
 
 func TestCheckVariantSelectorInService(t *testing.T) {
+	t.Parallel()
+
 	const (
 		variantLabel   = "pipecd.dev/variant"
 		primaryVariant = "primary"
diff --git a/pkg/app/piped/executor/lambda/lambda_test.go b/pkg/app/piped/executor/lambda/lambda_test.go
index 165af146a2..c4d8ea988f 100644
--- a/pkg/app/piped/executor/lambda/lambda_test.go
+++ b/pkg/app/piped/executor/lambda/lambda_test.go
@@ -27,6 +27,8 @@ import (
 )
 
 func TestConfigureTrafficRouting(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name      string
 		version   string
@@ -171,6 +173,8 @@ func (g *fakeGitClient) Clone(_ context.Context, _, _, _, _ string) (git.Repo, e
 }
 
 func TestPrepareZipFromSource(t *testing.T) {
+	t.Parallel()
+
 	gc := &fakeGitClient{
 		repo: &fakeRepo{
 			source: "testdata/raw",
diff --git a/pkg/app/piped/executor/terraform/BUILD.bazel b/pkg/app/piped/executor/terraform/BUILD.bazel
index 7ab118a290..6b6b7bc21f 100644
--- a/pkg/app/piped/executor/terraform/BUILD.bazel
+++ b/pkg/app/piped/executor/terraform/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -17,10 +17,3 @@ go_library(
         "//pkg/model:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["terraform_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/executor/terraform/terraform_test.go b/pkg/app/piped/executor/terraform/terraform_test.go
deleted file mode 100644
index b2dcb81a31..0000000000
--- a/pkg/app/piped/executor/terraform/terraform_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package terraform
diff --git a/pkg/app/piped/executor/waitapproval/waitapproval_test.go b/pkg/app/piped/executor/waitapproval/waitapproval_test.go
index 0c7177d456..0d99e372f1 100644
--- a/pkg/app/piped/executor/waitapproval/waitapproval_test.go
+++ b/pkg/app/piped/executor/waitapproval/waitapproval_test.go
@@ -74,6 +74,8 @@ type fakeNotifier struct{}
 func (n *fakeNotifier) Notify(_ model.NotificationEvent) {}
 
 func TestValidateApproverNum(t *testing.T) {
+	t.Parallel()
+
 	ctx := context.Background()
 
 	ac := &fakeAPIClient{
diff --git a/pkg/app/piped/livestatestore/kubernetes/reflector_test.go b/pkg/app/piped/livestatestore/kubernetes/reflector_test.go
index 7147abda2a..6994396b69 100644
--- a/pkg/app/piped/livestatestore/kubernetes/reflector_test.go
+++ b/pkg/app/piped/livestatestore/kubernetes/reflector_test.go
@@ -25,6 +25,8 @@ import (
 )
 
 func TestResourceMatcher(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name string
 		cfg  config.KubernetesAppStateInformer
@@ -71,10 +73,14 @@ func TestResourceMatcher(t *testing.T) {
 	}
 
 	for _, tc := range testcases {
+		tc := tc
 		m := newResourceMatcher(tc.cfg)
 		for gvk, expected := range tc.gvks {
 			desc := fmt.Sprintf("%s: %v", tc.name, gvk)
+			gvk, expected := gvk, expected
 			t.Run(desc, func(t *testing.T) {
+				t.Parallel()
+
 				matched := m.Match(gvk)
 				assert.Equal(t, expected, matched)
 			})
diff --git a/pkg/app/piped/logpersister/persister_test.go b/pkg/app/piped/logpersister/persister_test.go
index 82e6170bc9..22ef642f6e 100644
--- a/pkg/app/piped/logpersister/persister_test.go
+++ b/pkg/app/piped/logpersister/persister_test.go
@@ -51,6 +51,8 @@ func (c *fakeAPIClient) NumberOfReportStageLogsFromLastCheckpoint() int {
 }
 
 func TestPersister(t *testing.T) {
+	t.Parallel()
+
 	apiClient := &fakeAPIClient{}
 	p := NewPersister(apiClient, zap.NewNop())
 	p.stalePeriod = 0
diff --git a/pkg/app/piped/metadatastore/store_test.go b/pkg/app/piped/metadatastore/store_test.go
index d50ba61558..51c6bab0ae 100644
--- a/pkg/app/piped/metadatastore/store_test.go
+++ b/pkg/app/piped/metadatastore/store_test.go
@@ -56,6 +56,8 @@ func (c *fakeAPIClient) SaveStageMetadata(ctx context.Context, req *pipedservice
 }
 
 func TestStore(t *testing.T) {
+	t.Parallel()
+
 	ac := &fakeAPIClient{
 		shared: make(map[string]string, 0),
 		stages: make(map[string]metadata, 0),
diff --git a/pkg/app/piped/notifier/matcher_test.go b/pkg/app/piped/notifier/matcher_test.go
index 5b5bc88820..ab127c4058 100644
--- a/pkg/app/piped/notifier/matcher_test.go
+++ b/pkg/app/piped/notifier/matcher_test.go
@@ -24,6 +24,8 @@ import (
 )
 
 func TestMatch(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name      string
 		config    config.NotificationRoute
diff --git a/pkg/app/piped/planner/ecs/pipeline_test.go b/pkg/app/piped/planner/ecs/pipeline_test.go
index b273cf7379..489e084798 100644
--- a/pkg/app/piped/planner/ecs/pipeline_test.go
+++ b/pkg/app/piped/planner/ecs/pipeline_test.go
@@ -10,6 +10,8 @@ import (
 )
 
 func TestBuildQuickSyncPipeline(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name             string
 		wantAutoRollback bool
diff --git a/pkg/app/piped/planner/kubernetes/kubernetes_test.go b/pkg/app/piped/planner/kubernetes/kubernetes_test.go
index 816864372d..db09eeb813 100644
--- a/pkg/app/piped/planner/kubernetes/kubernetes_test.go
+++ b/pkg/app/piped/planner/kubernetes/kubernetes_test.go
@@ -13,6 +13,8 @@ import (
 )
 
 func TestDecideStrategy(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name            string
 		olds            []provider.Manifest
@@ -399,6 +401,8 @@ func TestDecideStrategy(t *testing.T) {
 }
 
 func TestDetermineVersion(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
@@ -440,6 +444,8 @@ func TestDetermineVersion(t *testing.T) {
 }
 
 func TestDetermineVersions(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		manifests     string
@@ -526,6 +532,8 @@ func TestDetermineVersions(t *testing.T) {
 }
 
 func TestCheckImageChange(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name          string
 		oldManifests  string
diff --git a/pkg/app/piped/planner/kubernetes/pipeline_test.go b/pkg/app/piped/planner/kubernetes/pipeline_test.go
index 427477d919..78254dc8ef 100644
--- a/pkg/app/piped/planner/kubernetes/pipeline_test.go
+++ b/pkg/app/piped/planner/kubernetes/pipeline_test.go
@@ -11,6 +11,8 @@ import (
 )
 
 func TestBuildQuickSyncPipeline(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name             string
 		wantAutoRollback bool
@@ -39,6 +41,8 @@ func TestBuildQuickSyncPipeline(t *testing.T) {
 }
 
 func TestBuildProgressivePipeline(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name             string
 		wantAutoRollback bool
diff --git a/pkg/app/piped/planpreview/BUILD.bazel b/pkg/app/piped/planpreview/BUILD.bazel
index 71c5ce62cc..bfc980516d 100644
--- a/pkg/app/piped/planpreview/BUILD.bazel
+++ b/pkg/app/piped/planpreview/BUILD.bazel
@@ -37,10 +37,7 @@ go_library(
 go_test(
     name = "go_default_test",
     size = "small",
-    srcs = [
-        "builder_test.go",
-        "handler_test.go",
-    ],
+    srcs = ["handler_test.go"],
     embed = [":go_default_library"],
     deps = [
         "//pkg/model:go_default_library",
diff --git a/pkg/app/piped/planpreview/builder_test.go b/pkg/app/piped/planpreview/builder_test.go
deleted file mode 100644
index 471c861fcb..0000000000
--- a/pkg/app/piped/planpreview/builder_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2021 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package planpreview
diff --git a/pkg/app/piped/planpreview/handler_test.go b/pkg/app/piped/planpreview/handler_test.go
index 914f913495..67f44c6215 100644
--- a/pkg/app/piped/planpreview/handler_test.go
+++ b/pkg/app/piped/planpreview/handler_test.go
@@ -53,6 +53,8 @@ func (b *testBuilder) Build(ctx context.Context, id string, cmd model.Command_Bu
 }
 
 func TestHandler(t *testing.T) {
+	t.Parallel()
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
diff --git a/pkg/app/piped/sourcedecrypter/decrypter_test.go b/pkg/app/piped/sourcedecrypter/decrypter_test.go
index 5d7a0c622b..e6aeee18b0 100644
--- a/pkg/app/piped/sourcedecrypter/decrypter_test.go
+++ b/pkg/app/piped/sourcedecrypter/decrypter_test.go
@@ -36,10 +36,13 @@ func (d testSecretDecrypter) Decrypt(text string) (string, error) {
 }
 
 func TestDecryptSecrets(t *testing.T) {
+	t.Parallel()
+
 	workspace, err := os.MkdirTemp("", "test-decrypt-secrets")
 	require.NoError(t, err)
-	defer os.RemoveAll(workspace)
-
+	t.Cleanup(func() {
+		os.RemoveAll(workspace)
+	})
 	dcr := testSecretDecrypter{
 		prefix: "decrypted-",
 	}
diff --git a/pkg/app/piped/statsreporter/BUILD.bazel b/pkg/app/piped/statsreporter/BUILD.bazel
index 6af640bb6d..2b3b1fc860 100644
--- a/pkg/app/piped/statsreporter/BUILD.bazel
+++ b/pkg/app/piped/statsreporter/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -11,11 +11,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["reporter_test.go"],
-    data = glob(["testdata/**"]),
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/statsreporter/reporter_test.go b/pkg/app/piped/statsreporter/reporter_test.go
deleted file mode 100644
index 1ef9afc9d5..0000000000
--- a/pkg/app/piped/statsreporter/reporter_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package statsreporter
diff --git a/pkg/app/piped/toolregistry/BUILD.bazel b/pkg/app/piped/toolregistry/BUILD.bazel
index a4cb331c2f..a61a9656d9 100644
--- a/pkg/app/piped/toolregistry/BUILD.bazel
+++ b/pkg/app/piped/toolregistry/BUILD.bazel
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
@@ -15,10 +15,3 @@ go_library(
         "@org_uber_go_zap//:go_default_library",
     ],
 )
-
-go_test(
-    name = "go_default_test",
-    size = "small",
-    srcs = ["registry_test.go"],
-    embed = [":go_default_library"],
-)
diff --git a/pkg/app/piped/toolregistry/registry_test.go b/pkg/app/piped/toolregistry/registry_test.go
deleted file mode 100644
index 1797605e16..0000000000
--- a/pkg/app/piped/toolregistry/registry_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2020 The PipeCD Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package toolregistry
diff --git a/pkg/app/piped/trigger/determiner_test.go b/pkg/app/piped/trigger/determiner_test.go
index 8ad5d19e9c..4e67219dd9 100644
--- a/pkg/app/piped/trigger/determiner_test.go
+++ b/pkg/app/piped/trigger/determiner_test.go
@@ -21,6 +21,8 @@ import (
 )
 
 func TestIsTouchedByChangedFiles(t *testing.T) {
+	t.Parallel()
+
 	testcases := []struct {
 		name         string
 		appDir       string