Switch to current directory in tests

Lots of the module stuff (and more) depends on the "context" of the
module, so being in the right directory when we run the imports.Process
from the tests is important.

pkg/scaffold/scaffold.go

@@ -52,6 +52,8 @@ type Scaffold struct {
 	ProjectPath string
 
 	GetWriter func(path string) (io.Writer, error)
+
+	FileExists func(path string) bool
 }
 
 func (s *Scaffold) setFieldsAndValidate(t input.File) error {
@@ -141,6 +143,12 @@ func (s *Scaffold) Execute(options input.Options, files ...input.File) error {
 	if s.GetWriter == nil {
 		s.GetWriter = (&FileWriter{}).WriteCloser
 	}
+	if s.FileExists == nil {
+		s.FileExists = func(path string) bool {
+			_, err := os.Stat(path)
+			return err == nil
+		}
+	}
 
 	if err := s.defaultOptions(&options); err != nil {
 		return err
@@ -181,7 +189,7 @@ func (s *Scaffold) doFile(e input.File) error {
 	}
 
 	// Check if the file to write already exists
-	if _, err := os.Stat(i.Path); err == nil {
+	if s.FileExists(i.Path) {
 		switch i.IfExistsAction {
 		case input.Overwrite:
 		case input.Skip:

pkg/scaffold/scaffoldtest/scaffoldtest.go

@@ -42,8 +42,7 @@ type TestResult struct {
 }
 
 func getProjectRoot() string {
-	gopath := os.Getenv("GOPATH")
-	return path.Join(gopath, "src", "sigs.k8s.io", "kubebuilder")
+	return path.Join(build.Default.GOPATH, "src", "sigs.k8s.io", "kubebuilder")
 }
 
 // ProjectPath is the path to the controller-tools/testdata project file
@@ -66,6 +65,7 @@ func Options() input.Options {
 
 // NewTestScaffold returns a new Scaffold and TestResult instance for testing
 func NewTestScaffold(writeToPath, goldenPath string) (*scaffold.Scaffold, *TestResult) {
+	projRoot := getProjectRoot()
 	r := &TestResult{}
 	// Setup scaffold
 	s := &scaffold.Scaffold{
@@ -74,12 +74,20 @@ func NewTestScaffold(writeToPath, goldenPath string) (*scaffold.Scaffold, *TestR
 			gomega.Expect(path).To(gomega.Equal(writeToPath))
 			return &r.Actual, nil
 		},
-		ProjectPath: filepath.Join(getProjectRoot(), "testdata", "gopath", "src", "project"),
+		FileExists: func(path string) bool {
+			return path != writeToPath
+		},
+		ProjectPath: filepath.Join(projRoot, "testdata", "gopath", "src", "project"),
+	}
+	oldGoPath := build.Default.GOPATH
+	build.Default.GOPATH = filepath.Join(projRoot, "testdata", "gopath")
+	defer func() { build.Default.GOPATH = oldGoPath }()
+	if _, err := os.Stat(build.Default.GOPATH); err != nil {
+		panic(err)
 	}
-	build.Default.GOPATH = filepath.Join(getProjectRoot(), "testdata", "gopath")
 
 	if len(goldenPath) > 0 {
-		b, err := ioutil.ReadFile(filepath.Join(getProjectRoot(), "testdata", "gopath", "src", "project", goldenPath))
+		b, err := ioutil.ReadFile(filepath.Join(projRoot, "testdata", "gopath", "src", "project", goldenPath))
 		gomega.Expect(err).NotTo(gomega.HaveOccurred())
 		r.Golden = string(b)
 	}