config/module: test that symlink that exists will be overwritten

config/module/get_file.go

@@ -12,7 +12,14 @@ import (
 type FileGetter struct{}
 
 func (g *FileGetter) Get(dst string, u *url.URL) error {
-	fi, err := os.Stat(dst)
+	// The source path must exist and be a directory to be usable.
+	if fi, err := os.Stat(u.Path); err != nil {
+		return fmt.Errorf("source path error: %s", err)
+	} else if !fi.IsDir() {
+		return fmt.Errorf("source path must be a directory")
+	}
+
+	fi, err := os.Lstat(dst)
 	if err != nil && !os.IsNotExist(err) {
 		return err
 	}
@@ -20,16 +27,14 @@ func (g *FileGetter) Get(dst string, u *url.URL) error {
 	// If the destination already exists, it must be a symlink
 	if err == nil {
 		mode := fi.Mode()
-		if mode&os.ModeSymlink != 0 {
+		if mode&os.ModeSymlink == 0 {
 			return fmt.Errorf("destination exists and is not a symlink")
 		}
-	}
 
-	// The source path must exist and be a directory to be usable.
-	if fi, err := os.Stat(u.Path); err != nil {
-		return fmt.Errorf("source path error: %s", err)
-	} else if !fi.IsDir() {
-		return fmt.Errorf("source path must be a directory")
+		// Remove the destination
+		if err := os.Remove(dst); err != nil {
+			return err
+		}
 	}
 
 	// Create all the parent directories

config/module/get_file_test.go

@@ -20,6 +20,15 @@ func TestFileGetter(t *testing.T) {
 		t.Fatalf("err: %s", err)
 	}
 
+	// Verify the destination folder is a symlink
+	fi, err := os.Lstat(dst)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if fi.Mode()&os.ModeSymlink == 0 {
+		t.Fatal("destination is not a symlink")
+	}
+
 	// Verify the main file exists
 	mainPath := filepath.Join(dst, "main.tf")
 	if _, err := os.Stat(mainPath); err != nil {
@@ -65,6 +74,36 @@ func TestFileGetter_dir(t *testing.T) {
 	}
 }
 
+func TestFileGetter_dirSymlink(t *testing.T) {
+	g := new(FileGetter)
+	dst := tempDir(t)
+	dst2 := tempDir(t)
+
+	// Make parents
+	if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if err := os.MkdirAll(dst2, 0755); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Make a symlink
+	if err := os.Symlink(dst2, dst); err != nil {
+		t.Fatalf("err: %s")
+	}
+
+	// With a dir that exists that isn't a symlink
+	if err := g.Get(dst, testModuleURL("basic")); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Verify the main file exists
+	mainPath := filepath.Join(dst, "main.tf")
+	if _, err := os.Stat(mainPath); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
 func testModuleURL(n string) *url.URL {
 	u, err := url.Parse(testModule(n))
 	if err != nil {