diff --git a/linters/codequality/rules.go b/linters/codequality/rules.go
index af9de46..79fa409 100644
--- a/linters/codequality/rules.go
+++ b/linters/codequality/rules.go
@@ -31,7 +31,7 @@ Linter | Why?
 
 This rule will be satisfied, iff for each of these linters:
 - **Either** there is a configuration file for this linter in the project
-- **Or** the linter is a dependency of the project`,
+- **Or** the linter is a dependency of the project (preferably a dev dependency)`,
 	Weight: 1,
 }
 
diff --git a/linters/testing/linter.go b/linters/testing/linter.go
index 51a2c5e..3f6a455 100644
--- a/linters/testing/linter.go
+++ b/linters/testing/linter.go
@@ -1,4 +1,4 @@
-package template
+package testing
 
 import (
 	"fmt"
@@ -48,10 +48,17 @@ func (l *TestingLinter) LintProject(project api.Project) (api.Report, error) {
 }
 
 func (l *TestingLinter) ScoreRuleHasTests(report *api.Report, project api.Project) {
+	if len(project.PythonFiles) == 0 {
+		report.Scores[RuleHasTests] = 0
+		return
+	}
+
 	testFiles := project.PythonFiles.Filter(func(filename string) bool {
 		return strings.HasSuffix(filename, "_test.py") || strings.HasPrefix(path.Base(filename), "test_")
 	})
 
+	// Possible TODO: have a config option for the target amount of tests per file?
+
 	// there should be at 1 test file per 4 non-test Python files.
 	report.Scores[RuleHasTests] = 100 * (float64(len(testFiles)) * 4 / float64(len(project.PythonFiles)-len(testFiles)))
 }
diff --git a/linters/testing/linter_test.go b/linters/testing/linter_test.go
new file mode 100644
index 0000000..5e186d5
--- /dev/null
+++ b/linters/testing/linter_test.go
@@ -0,0 +1,87 @@
+package testing_test
+
+import (
+	"fmt"
+	stdtesting "testing"
+
+	"github.com/bvobart/mllint/api"
+	"github.com/bvobart/mllint/config"
+	"github.com/bvobart/mllint/linters/testing"
+	"github.com/bvobart/mllint/linters/testutils"
+	"github.com/bvobart/mllint/utils"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTestingLinter(t *stdtesting.T) {
+	linter := testing.NewLinter()
+	require.Equal(t, "Testing", linter.Name())
+
+	suite := testutils.NewLinterTestSuite(linter, []testutils.LinterTest{
+		{
+			Name: "NoTestsNoFiles",
+			Dir:  ".",
+			Expect: func(report api.Report, err error) {
+				require.NoError(t, err)
+				require.EqualValues(t, 0, report.Scores[testing.RuleHasTests])
+				require.EqualValues(t, 0, report.Scores[testing.RuleTestsPass])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestsFolder])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestCoverage])
+			},
+		},
+		{
+			Name:    "NoTestsSixteenFiles",
+			Dir:     ".",
+			Options: testutils.NewOptions().UsePythonFiles(createPythonFilenames(16)),
+			Expect: func(report api.Report, err error) {
+				require.NoError(t, err)
+				require.EqualValues(t, 0, report.Scores[testing.RuleHasTests])
+				require.EqualValues(t, 0, report.Scores[testing.RuleTestsPass])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestsFolder])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestCoverage])
+			},
+		},
+		{
+			Name:    "OneTestSixteenFiles",
+			Dir:     ".",
+			Options: testutils.NewOptions().UsePythonFiles(createPythonFilenames(16).Concat(createPythonTestFilenames(1))),
+			Expect: func(report api.Report, err error) {
+				require.NoError(t, err)
+				require.EqualValues(t, 25, report.Scores[testing.RuleHasTests])
+				require.EqualValues(t, 0, report.Scores[testing.RuleTestsPass])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestsFolder])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestCoverage])
+			},
+		},
+		{
+			Name:    "FourTestsSixteenFiles",
+			Dir:     ".",
+			Options: testutils.NewOptions().UsePythonFiles(createPythonFilenames(16).Concat(createPythonTestFilenames(4))),
+			Expect: func(report api.Report, err error) {
+				require.NoError(t, err)
+				require.EqualValues(t, 100, report.Scores[testing.RuleHasTests])
+				require.EqualValues(t, 0, report.Scores[testing.RuleTestsPass])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestsFolder])
+				// require.Equal(t, 0, report.Scores[testing.RuleTestCoverage])
+			},
+		},
+	})
+
+	suite.DefaultOptions().WithConfig(config.Default())
+	suite.RunAll(t)
+}
+
+func createPythonFilenames(n int) utils.Filenames {
+	files := make(utils.Filenames, n)
+	for i := 0; i < n; i++ {
+		files[i] = fmt.Sprint("file", i, ".py")
+	}
+	return files
+}
+
+func createPythonTestFilenames(n int) utils.Filenames {
+	files := make(utils.Filenames, n)
+	for i := 0; i < n; i++ {
+		files[i] = fmt.Sprint("file", i, "_test.py")
+	}
+	return files
+}
diff --git a/linters/testing/rules.go b/linters/testing/rules.go
index b826c08..e0d2bd1 100644
--- a/linters/testing/rules.go
+++ b/linters/testing/rules.go
@@ -1,4 +1,4 @@
-package template
+package testing
 
 import "github.com/bvobart/mllint/api"