printer: incorporate review comments

printer/printer_test.go

@@ -11,13 +11,11 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-type mockWriter struct {
-	buffer []byte
-}
+type mockWriter []byte
 
 func (w *mockWriter) Write(b []byte) (n int, err error) {
-	w.buffer = append(w.buffer, b...)
-	return len(w.buffer) - len(b), nil
+	*w = append(*w, b...)
+	return len(*w) - len(b), nil
 }
 
 func TestPrintT(t *testing.T) {
@@ -34,39 +32,48 @@ func TestPrintT(t *testing.T) {
 	t.Run("should execute template", func(t *testing.T) {
 		tpl := `testing template {{.ID}}`
 		PrintT(tpl, ts)
+		assert.Len(t, GetLines(), 1)
+
+		Flush()
 		assert.Equal(t, "testing template 123", printer.Lines[0])
 	})
 
 	t.Run("should fail to execute, no method or field", func(t *testing.T) {
 		Clean()
 		tpl := `testing template {{.Name}}`
 		PrintT(tpl, ts)
+		assert.Len(t, GetErrorLines(), 1)
+
+		Flush()
 		assert.Equal(t, "Can't print the message using the provided template: "+tpl, printer.ErrorLines[0])
 	})
 }
 
 func TestFlush(t *testing.T) {
-	mw := &mockWriter{}
-	printer.writer = mw
 	printer.Format = FormatJSON
 
 	t.Run("should print a line in JSON format", func(t *testing.T) {
-		mw.buffer = []byte{}
+		mw := &mockWriter{}
+		printer.writer = mw
 		Clean()
 
 		Print("test string")
-		Flush()
+		assert.Len(t, GetLines(), 1)
 
-		assert.Equal(t, "[\n  \"test string\"\n]\n", string(mw.buffer))
+		Flush()
+		assert.Equal(t, "[\n  \"test string\"\n]\n", string(*mw))
 	})
 
 	t.Run("should print multi line in JSON format", func(t *testing.T) {
-		mw.buffer = []byte{}
-		Clean()
+		mw := &mockWriter{}
+		printer.writer = mw
 
+		Clean()
 		Print("test string-1")
 		Print("test string-2")
+		assert.Len(t, GetLines(), 2)
+
 		Flush()
-		assert.Equal(t, "[\n  \"test string-1\",\n  \"test string-2\"\n]\n", string(mw.buffer))
+		assert.Equal(t, "[\n  \"test string-1\",\n  \"test string-2\"\n]\n", string(*mw))
 	})
 }