test/integration: run parallel tests concurrently with serial tests

Signed-off-by: Monis Khan <mok@vmware.com>

test/integration/main_test.go

@@ -0,0 +1,91 @@
+// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package integration
+
+import (
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+	"unsafe"
+
+	"go.pinniped.dev/test/testlib"
+)
+
+func TestMain(m *testing.M) {
+	splitIntegrationTestsIntoBuckets(m)
+	os.Exit(m.Run())
+}
+
+func splitIntegrationTestsIntoBuckets(m *testing.M) {
+	// this is some dark magic to set a private field
+	testsField := reflect.ValueOf(m).Elem().FieldByName("tests")
+	testsPointer := (*[]testing.InternalTest)(unsafe.Pointer(testsField.UnsafeAddr()))
+
+	tests := *testsPointer
+
+	if len(tests) == 0 {
+		return
+	}
+
+	var serialTests, parallelTests, finalTests []testing.InternalTest
+
+	for _, test := range tests {
+		test := test
+
+		// top level integration tests the end with the string _Parallel
+		// are indicating that they are safe to run in parallel with
+		// other serial tests (which Go does not let you easily express).
+		// top level tests that want the standard Go behavior of only running
+		// parallel tests with other parallel tests should use the regular
+		// t.Parallel() approach. this has no effect on any subtest.
+		if strings.HasSuffix(test.Name, "_Parallel") {
+			parallelTests = append(parallelTests, test)
+		} else {
+			serialTests = append(serialTests, test)
+		}
+	}
+
+	serialTest := testing.InternalTest{
+		Name: "TestIntegrationSerial",
+		F: func(t *testing.T) {
+			_ = testlib.IntegrationEnv(t) // make sure these tests do not run during unit tests
+			t.Parallel()                  // outer test runs in parallel always
+
+			for _, test := range serialTests {
+				test := test
+				t.Run(test.Name, func(t *testing.T) {
+					test.F(t) // inner serial tests do not run in parallel
+				})
+			}
+		},
+	}
+
+	parallelTest := testing.InternalTest{
+		Name: "TestIntegrationParallel",
+		F: func(t *testing.T) {
+			_ = testlib.IntegrationEnv(t) // make sure these tests do not run during unit tests
+			t.Parallel()                  // outer test runs in parallel always
+
+			for _, test := range parallelTests {
+				test := test
+				t.Run(test.Name, func(t *testing.T) {
+					t.Parallel() // inner parallel tests do run in parallel
+
+					test.F(t)
+				})
+			}
+		},
+	}
+
+	if len(serialTests) > 0 {
+		finalTests = append(finalTests, serialTest)
+	}
+
+	if len(parallelTests) > 0 {
+		finalTests = append(finalTests, parallelTest)
+	}
+
+	*testsPointer = finalTests
+}