Fix bug in multiple calls to file applier

dmcgowan · dmcgowan · commit 7d784dfeb6c7 · 2018-05-23T14:56:44.000-07:00
Ensure that file appliers create the same content every time
they are called.

Signed-off-by: Derek McGowan &lt;derek@mcgstyle.net&gt;
diff --git a/fs/fstest/file.go b/fs/fstest/file.go
@@ -24,18 +24,24 @@ func (a applyFn) Apply(root string) error {
 // CreateFile returns a file applier which creates a file as the
 // provided name with the given content and permission.
 func CreateFile(name string, content []byte, perm os.FileMode) Applier {
-	return writeFileStream(name, bytes.NewReader(content), perm)
+	f := func() io.Reader {
+		return bytes.NewReader(content)
+	}
+	return writeFileStream(name, f, perm)
 }
 
 // CreateRandomFile returns a file applier which creates a file with random
 // content of the given size using the given seed and permission.
 func CreateRandomFile(name string, seed, size int64, perm os.FileMode) Applier {
-	return writeFileStream(name, io.LimitReader(rand.New(rand.NewSource(seed)), size), perm)
+	f := func() io.Reader {
+		return io.LimitReader(rand.New(rand.NewSource(seed)), size)
+	}
+	return writeFileStream(name, f, perm)
 }
 
 // writeFileStream returns a file applier which creates a file as the
 // provided name with the given content from the provided i/o stream and permission.
-func writeFileStream(name string, stream io.Reader, perm os.FileMode) Applier {
+func writeFileStream(name string, stream func() io.Reader, perm os.FileMode) Applier {
 	return applyFn(func(root string) (retErr error) {
 		fullPath := filepath.Join(root, name)
 		f, err := os.OpenFile(fullPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
@@ -48,7 +54,7 @@ func writeFileStream(name string, stream io.Reader, perm os.FileMode) Applier {
 				retErr = err
 			}
 		}()
-		_, err = io.Copy(f, stream)
+		_, err = io.Copy(f, stream())
 		if err != nil {
 			return err
 		}
