gopy: add test for gofmt'd code

main_test.go

@@ -14,6 +14,35 @@ import (
 	"testing"
 )
 
+func TestGofmt(t *testing.T) {
+	exe, err := exec.LookPath("goimports")
+	if err != nil {
+		switch e := err.(type) {
+		case *exec.Error:
+			if e.Err == exec.ErrNotFound {
+				exe, err = exec.LookPath("gofmt")
+			}
+		}
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cmd := exec.Command(exe, "-d", ".")
+	buf := new(bytes.Buffer)
+	cmd.Stdout = buf
+	cmd.Stderr = buf
+
+	err = cmd.Run()
+	if err != nil {
+		t.Fatalf("error running %s:\n%s\n%v", exe, string(buf.Bytes()), err)
+	}
+
+	if len(buf.Bytes()) != 0 {
+		t.Errorf("some files were not gofmt'ed:\n%s\n", string(buf.Bytes()))
+	}
+}
+
 type pkg struct {
 	path string
 	want []byte