1 files changed, 138 insertions, 33 deletions
diff --git a/src/testing/testing_test.go b/src/testing/testing_test.go
index 4a9303952e..af6035fd27 100644
--- a/src/testing/testing_test.go
+++ b/src/testing/testing_test.go
@@ -13,6 +13,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"slices"
 	"strings"
 	"sync"
@@ -200,64 +201,168 @@ func TestSetenv(t *testing.T) {
 	}
 }
 
-func TestSetenvWithParallelAfterSetenv(t *testing.T) {
-	defer func() {
-		want := "testing: t.Parallel called after t.Setenv; cannot set environment variables in parallel tests"
-		if got := recover(); got != want {
-			t.Fatalf("expected panic; got %#v want %q", got, want)
-		}
-	}()
+func expectParallelConflict(t *testing.T) {
+	want := testing.ParallelConflict
+	if got := recover(); got != want {
+		t.Fatalf("expected panic; got %#v want %q", got, want)
+	}
+}
 
-	t.Setenv("GO_TEST_KEY_1", "value")
+func testWithParallelAfter(t *testing.T, fn func(*testing.T)) {
+	defer expectParallelConflict(t)
 
+	fn(t)
 	t.Parallel()
 }
 
-func TestSetenvWithParallelBeforeSetenv(t *testing.T) {
-	defer func() {
-		want := "testing: t.Setenv called after t.Parallel; cannot set environment variables in parallel tests"
-		if got := recover(); got != want {
-			t.Fatalf("expected panic; got %#v want %q", got, want)
-		}
-	}()
+func testWithParallelBefore(t *testing.T, fn func(*testing.T)) {
+	defer expectParallelConflict(t)
 
 	t.Parallel()
-
-	t.Setenv("GO_TEST_KEY_1", "value")
+	fn(t)
 }
 
-func TestSetenvWithParallelParentBeforeSetenv(t *testing.T) {
+func testWithParallelParentBefore(t *testing.T, fn func(*testing.T)) {
 	t.Parallel()
 
 	t.Run("child", func(t *testing.T) {
-		defer func() {
-			want := "testing: t.Setenv called after t.Parallel; cannot set environment variables in parallel tests"
-			if got := recover(); got != want {
-				t.Fatalf("expected panic; got %#v want %q", got, want)
-			}
-		}()
+		defer expectParallelConflict(t)
 
-		t.Setenv("GO_TEST_KEY_1", "value")
+		fn(t)
 	})
 }
 
-func TestSetenvWithParallelGrandParentBeforeSetenv(t *testing.T) {
+func testWithParallelGrandParentBefore(t *testing.T, fn func(*testing.T)) {
 	t.Parallel()
 
 	t.Run("child", func(t *testing.T) {
 		t.Run("grand-child", func(t *testing.T) {
-			defer func() {
-				want := "testing: t.Setenv called after t.Parallel; cannot set environment variables in parallel tests"
-				if got := recover(); got != want {
-					t.Fatalf("expected panic; got %#v want %q", got, want)
-				}
-			}()
+			defer expectParallelConflict(t)
 
-			t.Setenv("GO_TEST_KEY_1", "value")
+			fn(t)
 		})
 	})
 }
 
+func tSetenv(t *testing.T) {
+	t.Setenv("GO_TEST_KEY_1", "value")
+}
+
+func TestSetenvWithParallelAfter(t *testing.T) {
+	testWithParallelAfter(t, tSetenv)
+}
+
+func TestSetenvWithParallelBefore(t *testing.T) {
+	testWithParallelBefore(t, tSetenv)
+}
+
+func TestSetenvWithParallelParentBefore(t *testing.T) {
+	testWithParallelParentBefore(t, tSetenv)
+}
+
+func TestSetenvWithParallelGrandParentBefore(t *testing.T) {
+	testWithParallelGrandParentBefore(t, tSetenv)
+}
+
+func tChdir(t *testing.T) {
+	t.Chdir(t.TempDir())
+}
+
+func TestChdirWithParallelAfter(t *testing.T) {
+	testWithParallelAfter(t, tChdir)
+}
+
+func TestChdirWithParallelBefore(t *testing.T) {
+	testWithParallelBefore(t, tChdir)
+}
+
+func TestChdirWithParallelParentBefore(t *testing.T) {
+	testWithParallelParentBefore(t, tChdir)
+}
+
+func TestChdirWithParallelGrandParentBefore(t *testing.T) {
+	testWithParallelGrandParentBefore(t, tChdir)
+}
+
+func TestChdir(t *testing.T) {
+	oldDir, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Chdir(oldDir)
+
+	tmp := t.TempDir()
+	rel, err := filepath.Rel(oldDir, tmp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, tc := range []struct {
+		name, dir, pwd string
+		extraChdir     bool
+	}{
+		{
+			name: "absolute",
+			dir:  tmp,
+			pwd:  tmp,
+		},
+		{
+			name: "relative",
+			dir:  rel,
+			pwd:  tmp,
+		},
+		{
+			name: "current (absolute)",
+			dir:  oldDir,
+			pwd:  oldDir,
+		},
+		{
+			name: "current (relative) with extra os.Chdir",
+			dir:  ".",
+			pwd:  oldDir,
+
+			extraChdir: true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if !filepath.IsAbs(tc.pwd) {
+				t.Fatalf("Bad tc.pwd: %q (must be absolute)", tc.pwd)
+			}
+
+			t.Chdir(tc.dir)
+
+			newDir, err := os.Getwd()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if newDir != tc.pwd {
+				t.Fatalf("failed to chdir to %q: getwd: got %q, want %q", tc.dir, newDir, tc.pwd)
+			}
+
+			switch runtime.GOOS {
+			case "windows", "plan9":
+				// Windows and Plan 9 do not use the PWD variable.
+			default:
+				if pwd := os.Getenv("PWD"); pwd != tc.pwd {
+					t.Fatalf("PWD: got %q, want %q", pwd, tc.pwd)
+				}
+			}
+
+			if tc.extraChdir {
+				os.Chdir("..")
+			}
+		})
+
+		newDir, err := os.Getwd()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if newDir != oldDir {
+			t.Fatalf("failed to restore wd to %s: getwd: %s", oldDir, newDir)
+		}
+	}
+}
+
 // testingTrueInInit is part of TestTesting.
 var testingTrueInInit = false