add more test for id package

internal/identifier/id.go

@@ -34,9 +34,10 @@ func (i ID) Extension() (exttype string, fileext string) {
 		if numberOfElements > 2 {
 			exttype = elements[numberOfElements - 2]
 			fileext = elements[numberOfElements - 1]
+		} else {
+			exttype = elements[numberOfElements - 1]
 		}
-		exttype = elements[numberOfElements - 1]
 	}
-	return
+	return exttype, fileext
 }
 

internal/identifier/id_test.go

@@ -34,6 +34,22 @@ func TestID(t *testing.T) {
 	assert.Equal(t, "", fileext)
 }
 
+func TestIDExt(t *testing.T) {
+	for _, v := range []struct {	File ID
+					ExpectedExt string
+					ExpectedType string }{
+		{ File: "file:///tmp/foo/bar/baz.txt", ExpectedExt: "", ExpectedType: "txt" },
+		{ File: "file:///tmp/foo/bar/baz.txt.gz", ExpectedExt: "gz", ExpectedType: "txt" },
+		{ File: "file:///tmp/foo/bar/baz.quuz.txt.gz", ExpectedExt: "gz", ExpectedType: "txt" },
+	} {
+		u := v.File.Parse()
+		assert.Equal(t, "file", u.Scheme)
+		filetype, fileext := v.File.Extension()
+		assert.Equal(t, v.ExpectedType, filetype)
+		assert.Equal(t, v.ExpectedExt, fileext)
+	}
+}
+
 func TestSetID(t *testing.T) {
 	var file ID = ID(fmt.Sprintf("file://%s", TempDir))
 	u := file.Parse()