Add test.

src/cmd/go/internal/clean/clean_test.go

@@ -1,24 +0,0 @@
-package clean
-
-import (
-	"os/exec"
-	"strings"
-	"testing"
-)
-
-func TestCleanCache(t *testing.T) {
-	cmd := exec.Command("go", "clean", "-cache")
-	// See issue 69997. GOCACHE must be an absolute path.
-	cmd.Env = append(cmd.Environ(), "GOCACHE='.cache'")
-	_, err := cmd.Output()
-
-	if err != nil {
-		ee, ok := err.(*exec.ExitError)
-		if !ok || ee.ExitCode() != 1 || !strings.Contains(string(ee.Stderr), "GOCACHE is not an absolute path") {
-			t.Errorf("\"go clean -cache\" failed. expected status 1 != %d; error: %s", ee.ExitCode(), ee.Stderr)
-		}
-	} else {
-		t.Errorf("expected go clean -cache to fail")
-	}
-
-}

src/cmd/go/testdata/script/clean_cache_n.txt

@@ -18,6 +18,11 @@ go clean -cache
 ! go clean -cache .
 stderr 'go: clean -cache cannot be used with package arguments'
 
+# GOCACHE must be an absolute path.
+env GOCACHE=.
+! go clean -cache
+stderr 'go: GOCACHE is not an absolute path'
+
 -- main.go --
 package main