Fix a bug in the e2e tests

When the test was going to fail, a goroutine would accidentally block
on writing to an unbuffered channel, and the spawnTestGoroutine helper
would wait for that goroutine to end on cleanup, causing the test to
hang forever while it was trying to fail.

(cherry picked from commit 2b93fdf357)

test/integration/cli_test.go

@@ -1,4 +1,4 @@
-// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2022 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 package integration
 
@@ -292,7 +292,7 @@ func runPinnipedLoginOIDC(
 	})
 
 	// Start a background goroutine to read stderr from the CLI and parse out the login URL.
-	loginURLChan := make(chan string)
+	loginURLChan := make(chan string, 1)
 	spawnTestGoroutine(t, func() (err error) {
 		t.Helper()
 		defer func() {
@@ -311,7 +311,7 @@ func runPinnipedLoginOIDC(
 		for scanner.Scan() {
 			loginURL, err := url.Parse(strings.TrimSpace(scanner.Text()))
 			if err == nil && loginURL.Scheme == "https" {
-				loginURLChan <- loginURL.String()
+				loginURLChan <- loginURL.String() // this channel is buffered so this will not block
 				return nil
 			}
 		}
@@ -320,7 +320,7 @@ func runPinnipedLoginOIDC(
 	})
 
 	// Start a background goroutine to read stdout from the CLI and parse out an ExecCredential.
-	credOutputChan := make(chan clientauthenticationv1beta1.ExecCredential)
+	credOutputChan := make(chan clientauthenticationv1beta1.ExecCredential, 1)
 	spawnTestGoroutine(t, func() (err error) {
 		defer func() {
 			closeErr := stdout.Close()
@@ -336,7 +336,7 @@ func runPinnipedLoginOIDC(
 		if err := json.NewDecoder(reader).Decode(&out); err != nil {
 			return fmt.Errorf("could not read ExecCredential from stdout: %w", err)
 		}
-		credOutputChan <- out
+		credOutputChan <- out // this channel is buffered so this will not block
 		return readAndExpectEmpty(reader)
 	})
 
@@ -391,6 +391,7 @@ func readAndExpectEmpty(r io.Reader) (err error) {
 	return nil
 }
 
+// Note: Callers should ensure that f eventually returns, otherwise this helper will hang forever in t.Cleanup.
 func spawnTestGoroutine(t *testing.T, f func() error) {
 	t.Helper()
 	var eg errgroup.Group

test/integration/e2e_test.go

@@ -182,7 +182,7 @@ func TestE2EFullIntegration(t *testing.T) { // nolint:gocyclo
 		})
 
 		// Start a background goroutine to read stderr from the CLI and parse out the login URL.
-		loginURLChan := make(chan string)
+		loginURLChan := make(chan string, 1)
 		spawnTestGoroutine(t, func() (err error) {
 			defer func() {
 				closeErr := stderrPipe.Close()
@@ -199,7 +199,7 @@ func TestE2EFullIntegration(t *testing.T) { // nolint:gocyclo
 			for scanner.Scan() {
 				loginURL, err := url.Parse(strings.TrimSpace(scanner.Text()))
 				if err == nil && loginURL.Scheme == "https" {
-					loginURLChan <- loginURL.String()
+					loginURLChan <- loginURL.String() // this channel is buffered so this will not block
 					return nil
 				}
 			}
@@ -207,7 +207,7 @@ func TestE2EFullIntegration(t *testing.T) { // nolint:gocyclo
 		})
 
 		// Start a background goroutine to read stdout from kubectl and return the result as a string.
-		kubectlOutputChan := make(chan string)
+		kubectlOutputChan := make(chan string, 1)
 		spawnTestGoroutine(t, func() (err error) {
 			defer func() {
 				closeErr := stdoutPipe.Close()
@@ -223,7 +223,7 @@ func TestE2EFullIntegration(t *testing.T) { // nolint:gocyclo
 				return err
 			}
 			t.Logf("kubectl output:\n%s\n", output)
-			kubectlOutputChan <- string(output)
+			kubectlOutputChan <- string(output) // this channel is buffered so this will not block
 			return nil
 		})