test(cmd/prometheus): speed up test execution by t.Parallel() when possible

turn some loops into subtests to make use of t.Parallel()

requires Go 1.22 to make use of https://go.dev/blog/loopvar-preview

Signed-off-by: machine424 <ayoubmrini424@gmail.com>

cmd/prometheus/main_test.go

@@ -125,6 +125,7 @@ func TestFailedStartupExitCode(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
 
 	fakeInputFile := "fake-input-file"
 	expectedExitStatus := 2
@@ -211,83 +212,125 @@ func TestWALSegmentSizeBounds(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
+
+	for _, tc := range []struct {
+		size     string
+		exitCode int
+	}{
+		{
+			size:     "9MB",
+			exitCode: 1,
+		},
+		{
+			size:     "257MB",
+			exitCode: 1,
+		},
+		{
+			size:     "10",
+			exitCode: 2,
+		},
+		{
+			size:     "1GB",
+			exitCode: 1,
+		},
+		{
+			size:     "12MB",
+			exitCode: 0,
+		},
+	} {
+		t.Run(tc.size, func(t *testing.T) {
+			t.Parallel()
+			prom := exec.Command(promPath, "-test.main", "--storage.tsdb.wal-segment-size="+tc.size, "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig, "--storage.tsdb.path="+filepath.Join(t.TempDir(), "data"))
+
+			// Log stderr in case of failure.
+			stderr, err := prom.StderrPipe()
+			require.NoError(t, err)
+			go func() {
+				slurp, _ := io.ReadAll(stderr)
+				t.Log(string(slurp))
+			}()
+
+			err = prom.Start()
+			require.NoError(t, err)
 
-	for size, expectedExitStatus := range map[string]int{"9MB": 1, "257MB": 1, "10": 2, "1GB": 1, "12MB": 0} {
+			if tc.exitCode == 0 {
-		prom := exec.Command(promPath, "-test.main", "--storage.tsdb.wal-segment-size="+size, "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig, "--storage.tsdb.path="+filepath.Join(t.TempDir(), "data"))
+				done := make(chan error, 1)
-
+				go func() { done <- prom.Wait() }()
-		// Log stderr in case of failure.
+				select {
-		stderr, err := prom.StderrPipe()
+				case err := <-done:
-		require.NoError(t, err)
+					require.Fail(t, "prometheus should be still running: %v", err)
-		go func() {
+				case <-time.After(startupTime):
-			slurp, _ := io.ReadAll(stderr)
+					prom.Process.Kill()
-			t.Log(string(slurp))
+					<-done
-		}()
+				}
-
+				return
-		err = prom.Start()
-		require.NoError(t, err)
-
-		if expectedExitStatus == 0 {
-			done := make(chan error, 1)
-			go func() { done <- prom.Wait() }()
-			select {
-			case err := <-done:
-				require.Fail(t, "prometheus should be still running: %v", err)
-			case <-time.After(startupTime):
-				prom.Process.Kill()
-				<-done
 			}
-			continue
-		}
 
-		err = prom.Wait()
+			err = prom.Wait()
-		require.Error(t, err)
+			require.Error(t, err)
-		var exitError *exec.ExitError
+			var exitError *exec.ExitError
-		require.ErrorAs(t, err, &exitError)
+			require.ErrorAs(t, err, &exitError)
-		status := exitError.Sys().(syscall.WaitStatus)
+			status := exitError.Sys().(syscall.WaitStatus)
-		require.Equal(t, expectedExitStatus, status.ExitStatus())
+			require.Equal(t, tc.exitCode, status.ExitStatus())
+		})
 	}
 }
 
 func TestMaxBlockChunkSegmentSizeBounds(t *testing.T) {
-	t.Parallel()
-
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
 
-	for size, expectedExitStatus := range map[string]int{"512KB": 1, "1MB": 0} {
+	for _, tc := range []struct {
-		prom := exec.Command(promPath, "-test.main", "--storage.tsdb.max-block-chunk-segment-size="+size, "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig, "--storage.tsdb.path="+filepath.Join(t.TempDir(), "data"))
+		size     string
-
+		exitCode int
-		// Log stderr in case of failure.
+	}{
-		stderr, err := prom.StderrPipe()
+		{
-		require.NoError(t, err)
+			size:     "512KB",
-		go func() {
+			exitCode: 1,
-			slurp, _ := io.ReadAll(stderr)
+		},
-			t.Log(string(slurp))
+		{
-		}()
+			size:     "1MB",
-
+			exitCode: 0,
-		err = prom.Start()
+		},
-		require.NoError(t, err)
+	} {
-
+		t.Run(tc.size, func(t *testing.T) {
-		if expectedExitStatus == 0 {
+			t.Parallel()
-			done := make(chan error, 1)
+			prom := exec.Command(promPath, "-test.main", "--storage.tsdb.max-block-chunk-segment-size="+tc.size, "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig, "--storage.tsdb.path="+filepath.Join(t.TempDir(), "data"))
-			go func() { done <- prom.Wait() }()
+
-			select {
+			// Log stderr in case of failure.
-			case err := <-done:
+			stderr, err := prom.StderrPipe()
-				require.Fail(t, "prometheus should be still running: %v", err)
+			require.NoError(t, err)
-			case <-time.After(startupTime):
+			go func() {
-				prom.Process.Kill()
+				slurp, _ := io.ReadAll(stderr)
-				<-done
+				t.Log(string(slurp))
+			}()
+
+			err = prom.Start()
+			require.NoError(t, err)
+
+			if tc.exitCode == 0 {
+				done := make(chan error, 1)
+				go func() { done <- prom.Wait() }()
+				select {
+				case err := <-done:
+					require.Fail(t, "prometheus should be still running: %v", err)
+				case <-time.After(startupTime):
+					prom.Process.Kill()
+					<-done
+				}
+				return
 			}
-			continue
-		}
 
-		err = prom.Wait()
+			err = prom.Wait()
-		require.Error(t, err)
+			require.Error(t, err)
-		var exitError *exec.ExitError
+			var exitError *exec.ExitError
-		require.ErrorAs(t, err, &exitError)
+			require.ErrorAs(t, err, &exitError)
-		status := exitError.Sys().(syscall.WaitStatus)
+			status := exitError.Sys().(syscall.WaitStatus)
-		require.Equal(t, expectedExitStatus, status.ExitStatus())
+			require.Equal(t, tc.exitCode, status.ExitStatus())
+		})
 	}
 }
 
@@ -353,6 +396,8 @@ func getCurrentGaugeValuesFor(t *testing.T, reg prometheus.Gatherer, metricNames
 }
 
 func TestAgentSuccessfulStartup(t *testing.T) {
+	t.Parallel()
+
 	prom := exec.Command(promPath, "-test.main", "--agent", "--web.listen-address=0.0.0.0:0", "--config.file="+agentConfig)
 	require.NoError(t, prom.Start())
 
@@ -371,6 +416,8 @@ func TestAgentSuccessfulStartup(t *testing.T) {
 }
 
 func TestAgentFailedStartupWithServerFlag(t *testing.T) {
+	t.Parallel()
+
 	prom := exec.Command(promPath, "-test.main", "--agent", "--storage.tsdb.path=.", "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig)
 
 	output := bytes.Buffer{}
@@ -398,6 +445,8 @@ func TestAgentFailedStartupWithServerFlag(t *testing.T) {
 }
 
 func TestAgentFailedStartupWithInvalidConfig(t *testing.T) {
+	t.Parallel()
+
 	prom := exec.Command(promPath, "-test.main", "--agent", "--web.listen-address=0.0.0.0:0", "--config.file="+promConfig)
 	require.NoError(t, prom.Start())
 
@@ -419,6 +468,7 @@ func TestModeSpecificFlags(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
 
 	testcases := []struct {
 		mode       string
@@ -433,6 +483,7 @@ func TestModeSpecificFlags(t *testing.T) {
 
 	for _, tc := range testcases {
 		t.Run(fmt.Sprintf("%s mode with option %s", tc.mode, tc.arg), func(t *testing.T) {
+			t.Parallel()
 			args := []string{"-test.main", tc.arg, t.TempDir(), "--web.listen-address=0.0.0.0:0"}
 
 			if tc.mode == "agent" {
@@ -484,6 +535,8 @@ func TestDocumentation(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.SkipNow()
 	}
+	t.Parallel()
+
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
@@ -508,6 +561,8 @@ func TestDocumentation(t *testing.T) {
 }
 
 func TestRwProtoMsgFlagParser(t *testing.T) {
+	t.Parallel()
+
 	defaultOpts := config.RemoteWriteProtoMsgs{
 		config.RemoteWriteProtoMsgV1, config.RemoteWriteProtoMsgV2,
 	}

cmd/prometheus/main_unix_test.go

@@ -34,6 +34,7 @@ func TestStartupInterrupt(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
 
 	port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))
 

cmd/prometheus/query_log_test.go

@@ -456,6 +456,7 @@ func TestQueryLog(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	t.Parallel()
 
 	cwd, err := os.Getwd()
 	require.NoError(t, err)
@@ -474,6 +475,7 @@ func TestQueryLog(t *testing.T) {
 					}
 
 					t.Run(p.String(), func(t *testing.T) {
+						t.Parallel()
 						p.run(t)
 					})
 				}