Add basic watchfs integration test.

Related issue: #13226.

Closes #13722.

PiperOrigin-RevId: 385954134

src/test/shell/integration/BUILD

@@ -806,6 +806,16 @@ sh_test(
     ],
 )
 
+sh_test(
+    name = "watchfs_test",
+    srcs = ["watchfs_test.sh"],
+    data = [
+        ":test-deps",
+        "@bazel_tools//tools/bash/runfiles",
+    ],
+    tags = ["no_windows"],
+)
+
 ########################################################################
 # Test suites.
 

src/test/shell/integration/watchfs_test.sh

@@ -0,0 +1,102 @@
+#!/bin/bash
+#
+# Copyright 2021 The Bazel Authors. All rights reserved.
+#
+# 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.
+
+# --- begin runfiles.bash initialization ---
+# Copy-pasted from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
+if [[ ! -d "${RUNFILES_DIR:-/dev/null}" && ! -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
+  if [[ -f "$0.runfiles_manifest" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
+  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
+  elif [[ -f "$0.runfiles/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
+    export RUNFILES_DIR="$0.runfiles"
+  fi
+fi
+if [[ -f "${RUNFILES_DIR:-/dev/null}/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
+  source "${RUNFILES_DIR}/bazel_tools/tools/bash/runfiles/runfiles.bash"
+elif [[ -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
+  source "$(grep -m1 "^bazel_tools/tools/bash/runfiles/runfiles.bash " \
+            "$RUNFILES_MANIFEST_FILE" | cut -d ' ' -f 2-)"
+else
+  echo >&2 "ERROR: cannot find @bazel_tools//tools/bash/runfiles:runfiles.bash"
+  exit 1
+fi
+# --- end runfiles.bash initialization ---
+
+source "$(rlocation "io_bazel/src/test/shell/integration_test_setup.sh")" \
+  || { echo "integration_test_setup.sh not found!" >&2; exit 1; }
+
+cd "$TEST_TMPDIR"
+
+function set_up() {
+    cd ${WORKSPACE_DIR}
+}
+
+function tear_down() {
+  # Start with a fresh bazel server.
+  bazel shutdown
+}
+
+function helper() {
+  startup_option="$1"
+  command_option="$2"
+  # Name of the calling function to end up using distinct packages.
+  local -r pkg=${FUNCNAME[1]}
+  mkdir $pkg || fail "mkdir $pkg"
+  cat > "$pkg/BUILD" << 'EOF'
+genrule(
+    name = "foo",
+    srcs = ["whocares.in"],
+    outs = ["foo.out"],
+    cmd = "touch $@",
+)
+EOF
+  touch "$pkg/whocares.in"
+  bazel $startup_option build $command_option "//$pkg:foo" &> "$TEST_log" \
+    || fail "Expected success."
+  bazel $startup_option build $command_option "//$pkg:foo" \
+    --record_full_profiler_data \
+    --noslim_profile \
+    --profile=/tmp/profile.log &> "$TEST_log" || fail "Expected success."
+  cat /tmp/profile.log | grep "VFS stat" > "$TEST_log" \
+    || fail "Missing profile file."
+}
+
+function test_nowatchfs() {
+  helper "" ""
+  local -r pkg=${FUNCNAME[0]}
+  expect_log "VFS stat.*${pkg}/whocares.in"
+}
+
+function test_startup() {
+  helper "--watchfs" ""
+  local -r pkg=${FUNCNAME[0]}
+  expect_not_log "VFS stat.*${pkg}/whocares.in"
+}
+
+function test_command() {
+  helper "" "--watchfs"
+  local -r pkg=${FUNCNAME[0]}
+  expect_not_log "VFS stat.*${pkg}/whocares.in"
+}
+
+function test_both() {
+  helper "--watchfs" "--watchfs"
+  local -r pkg=${FUNCNAME[0]}
+  expect_not_log "VFS stat.*${pkg}/whocares.in"
+}
+
+run_suite "Integration tests for --watchfs."