Allow overriding the test parallelism. (#593)

* Allow overriding the test parallelism.

* Add comment for confusing default

kudo-test.yaml

@@ -6,3 +6,4 @@ testDirs:
 - ./test/integration
 startKUDO: true
 startControlPlane: true
+parallel: 4

pkg/apis/kudo/v1alpha1/test_types.go

@@ -36,6 +36,8 @@ type TestSuite struct {
 	SkipClusterDelete bool `json:"skipClusterDelete"`
 	// Override the default timeout of 30 seconds (in seconds).
 	Timeout int `json:"timeout"`
+	// The maximum number of tests to run at once (default: 8).
+	Parallel int `json:"parallel"`
 }
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

pkg/kudoctl/cmd/test.go

@@ -46,6 +46,7 @@ func newTestCmd() *cobra.Command {
 	startKUDO := false
 	skipDelete := false
 	skipClusterDelete := false
+	parallel := 0
 
 	options := kudo.TestSuite{}
 
@@ -141,6 +142,10 @@ For more detailed documentation, visit: https://kudo.dev/docs/testing`,
 				options.SkipClusterDelete = skipClusterDelete
 			}
 
+			if isSet(flags, "parallel") {
+				options.Parallel = parallel
+			}
+
 			if len(args) != 0 {
 				options.TestDirs = args
 			}
@@ -152,7 +157,7 @@ For more detailed documentation, visit: https://kudo.dev/docs/testing`,
 			return nil
 		},
 		Run: func(cmd *cobra.Command, args []string) {
-			testutils.RunTests("kudo", testToRun, func(t *testing.T) {
+			testutils.RunTests("kudo", testToRun, options.Parallel, func(t *testing.T) {
 				harness := test.Harness{
 					TestSuite: options,
 					T:         t,
@@ -174,6 +179,8 @@ For more detailed documentation, visit: https://kudo.dev/docs/testing`,
 	testCmd.Flags().BoolVar(&startKUDO, "start-kudo", false, "Start KUDO during the test run.")
 	testCmd.Flags().BoolVar(&skipDelete, "skip-delete", false, "If set, do not delete resources created during tests (helpful for debugging test failures, implies --skip-cluster-delete).")
 	testCmd.Flags().BoolVar(&skipClusterDelete, "skip-cluster-delete", false, "If set, do not delete the mocked control plane or kind cluster.")
+	// The default value here is only used for the help message. The default is actually enforced in RunTests.
+	testCmd.Flags().IntVar(&parallel, "parallel", 8, "The maximum number of tests to run at once.")
 
 	return testCmd
 }

pkg/test/utils/testing.go

@@ -13,7 +13,8 @@ import (
 // RunTests runs a Go test method without requiring the Go compiler.
 // This does not currently support test caching.
 // If testToRun is set to a non-empty string, it is passed as a `-run` argument to the go test harness.
-func RunTests(testName string, testToRun string, testFunc func(*testing.T)) {
+// If paralellism is set, it limits the number of concurrently running tests.
+func RunTests(testName string, testToRun string, parallelism int, testFunc func(*testing.T)) {
 	// Set the verbose test flag to true since we are not using the regular go test CLI.
 	flag.Set("test.v", "true")
 
@@ -23,6 +24,12 @@ func RunTests(testName string, testToRun string, testFunc func(*testing.T)) {
 		flag.Set("test.run", fmt.Sprintf("//%s", testToRun))
 	}
 
+	parallelismStr := "8"
+	if parallelism != 0 {
+		parallelismStr = fmt.Sprintf("%d", parallelism)
+	}
+	flag.Set("test.parallel", parallelismStr)
+
 	os.Exit(testing.MainStart(&testDeps{}, []testing.InternalTest{
 		{
 			Name: testName,