Clean up temp files more thoroughly after testing. (#7815)

Our test cases spew a lot of files and directories around $TMPDIR.  Make more
thorough use of the testing package's TempDir methods to ensure these are
cleaned up.

In a few cases, this required plumbing test contexts through existing helper
code. In a couple places an explicit path was required, to work around cases
where we do global setup during a TestMain function. Those cases probably
deserve more thorough cleansing (preferably with fire), but for now I have just
worked around it to keep focused on the cleanup.

internal/libs/autofile/autofile_test.go

@@ -25,11 +25,7 @@ func TestSIGHUP(t *testing.T) {
 	})
 
 	// First, create a temporary directory and move into it
-	dir, err := os.MkdirTemp("", "sighup_test")
-	require.NoError(t, err)
-	t.Cleanup(func() {
-		_ = os.RemoveAll(dir)
-	})
+	dir := t.TempDir()
 	require.NoError(t, os.Chdir(dir))
 
 	// Create an AutoFile in the temporary directory
@@ -48,9 +44,7 @@ func TestSIGHUP(t *testing.T) {
 	require.NoError(t, os.Rename(name, name+"_old"))
 
 	// Move into a different temporary directory
-	otherDir, err := os.MkdirTemp("", "sighup_test_other")
-	require.NoError(t, err)
-	t.Cleanup(func() { os.RemoveAll(otherDir) })
+	otherDir := t.TempDir()
 	require.NoError(t, os.Chdir(otherDir))
 
 	// Send SIGHUP to self.
@@ -112,7 +106,7 @@ func TestAutoFileSize(t *testing.T) {
 	defer cancel()
 
 	// First, create an AutoFile writing to a tempfile dir
-	f, err := os.CreateTemp("", "sighup_test")
+	f, err := os.CreateTemp(t.TempDir(), "sighup_test")
 	require.NoError(t, err)
 	require.NoError(t, f.Close())
 

internal/libs/autofile/group_test.go

@@ -132,11 +132,8 @@ func TestRotateFile(t *testing.T) {
 		}
 	}()
 
-	dir, err := os.MkdirTemp("", "rotate_test")
-	require.NoError(t, err)
-	defer os.RemoveAll(dir)
-	err = os.Chdir(dir)
-	require.NoError(t, err)
+	dir := t.TempDir()
+	require.NoError(t, os.Chdir(dir))
 
 	require.True(t, filepath.IsAbs(g.Head.Path))
 	require.True(t, filepath.IsAbs(g.Dir))

internal/libs/tempfile/tempfile_test.go

@@ -21,7 +21,7 @@ func TestWriteFileAtomic(t *testing.T) {
 		perm os.FileMode = 0600
 	)
 
-	f, err := os.CreateTemp("/tmp", "write-atomic-test-")
+	f, err := os.CreateTemp(t.TempDir(), "write-atomic-test-")
 	if err != nil {
 		t.Fatal(err)
 	}