Check that *FileArtifact implements Artifact at compile time

fileartifactprocessor.go

@@ -36,6 +36,8 @@ const (
 
 const DefaultWriteMode WriteMode = WriteOnceMode
 
+var _ Artifact = (*FileArtifact)(nil)
+
 // FileArtifact is a data structure that can be used by a SpecificationProcessor to generate file artifacts
 // that can be written by the FileArtifactProcessor.
 type FileArtifact struct {
@@ -54,11 +56,11 @@ func NewDirectoryArtifact(path string, fileMode os.FileMode, writeMode WriteMode
 	}
 }
 
-func (a FileArtifact) ID() ArtifactID {
+func (a *FileArtifact) ID() ArtifactID {
 	return ArtifactID(a.Path)
 }
 
-func (a FileArtifact) IsDir() bool {
+func (a *FileArtifact) IsDir() bool {
 	return a.FileMode&os.ModeDir != 0
 }