Create proper test to fully reproduce the issue on macOS

mafredri · mafredri · commit 7692c5d249ac · 2022-06-07T12:57:26.000+03:00
diff --git a/pty/ptytest/ptytest_test.go b/pty/ptytest/ptytest_test.go
@@ -2,7 +2,7 @@ package ptytest_test
 
 import (
 	"fmt"
-	"os/exec"
+	"strings"
 	"testing"
 
 	"github.com/spf13/cobra"
@@ -21,32 +21,36 @@ func TestPtytest(t *testing.T) {
 		pty.WriteLine("read")
 	})
 
-	// nolint:paralleltest
-	t.Run("Do not hang on Intel macOS", func(t *testing.T) {
-		cmd := exec.Command("sh", "-c", "echo hi, I will cause a hang")
-		pty := ptytest.New(t)
-		cmd.Stdin = pty.Input()
-		cmd.Stdout = pty.Output()
-		err := cmd.Run()
-		require.NoError(t, err)
-	})
+	t.Run("Cobra ptytest should not hang when output is not consumed", func(t *testing.T) {
+		t.Parallel()
 
-	// nolint:paralleltest
-	t.Run("CobraCommandWorksLinux", func(t *testing.T) {
-		// Example with cobra command instead of exec. More abstractions, but
-		// for some reason works on linux.
-		cmd := cobra.Command{
-			Use: "test",
-			RunE: func(cmd *cobra.Command, args []string) error {
-				fmt.Println("Hello world")
-				return nil
-			},
+		tests := []struct {
+			name   string
+			output string
+		}{
+			{name: "1024 is safe (does not exceed macOS buffer)", output: strings.Repeat(".", 1024)},
+			{name: "1025 exceeds macOS buffer (must not hang)", output: strings.Repeat(".", 1025)},
 		}
+		for _, tt := range tests {
+			tt := tt
+			// nolint:paralleltest // Avoid parallel test to more easily identify the issue.
+			t.Run(tt.name, func(t *testing.T) {
+				// Example with cobra command instead of exec. More abstractions, but
+				// for some reason works on linux.
+				cmd := cobra.Command{
+					Use: "test",
+					RunE: func(cmd *cobra.Command, args []string) error {
+						fmt.Fprint(cmd.OutOrStdout(), tt.output)
+						return nil
+					},
+				}
 
-		pty := ptytest.New(t)
-		cmd.SetIn(pty.Input())
-		cmd.SetOut(pty.Output())
-		err := cmd.Execute()
-		require.NoError(t, err)
+				pty := ptytest.New(t)
+				cmd.SetIn(pty.Input())
+				cmd.SetOut(pty.Output())
+				err := cmd.Execute()
+				require.NoError(t, err)
+			})
+		}
 	})
 }
