Merge pull request #4 from alevinval/master

(posix-writer) test coverage, simplify logic and faster clearLines()

Author: vbauerster

cwriter/writer.go

@@ -26,19 +26,12 @@ func New(w io.Writer) *Writer {
 
 // Flush flushes the underlying buffer
 func (w *Writer) Flush() error {
-	// do nothing if buffer is empty
-	if len(w.buf.Bytes()) == 0 {
+	// Do nothing if buffer is empty
+	if w.buf.Len() == 0 {
 		return nil
 	}
 	w.clearLines()
-
-	lines := 0
-	for _, b := range w.buf.Bytes() {
-		if b == '\n' {
-			lines++
-		}
-	}
-	w.lineCount = lines
+	w.lineCount = bytes.Count(w.buf.Bytes(), []byte("\n"))
 	_, err := w.out.Write(w.buf.Bytes())
 	w.buf.Reset()
 	return err

cwriter/writer_posix.go

@@ -8,10 +8,15 @@ import (
 	"unsafe"
 )
 
+var (
+	cursorUp           = fmt.Sprintf("%c[%dA", ESC, 1)
+	clearLine          = fmt.Sprintf("%c[2K\r", ESC)
+	clearCursorAndLine = cursorUp + clearLine
+)
+
 func (w *Writer) clearLines() {
 	for i := 0; i < w.lineCount; i++ {
-		fmt.Fprintf(w.out, "%c[%dA", ESC, 1) // move the cursor up
-		fmt.Fprintf(w.out, "%c[2K\r", ESC)   // clear the line
+		fmt.Fprint(w.out, clearCursorAndLine)
 	}
 }
 

cwriter/writer_posix_test.go

@@ -0,0 +1,36 @@
+// +build !windows
+
+package cwriter_test
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/vbauerster/mpb/cwriter"
+)
+
+var clearSequence = fmt.Sprintf("%c[%dA%c[2K\r", 27, 1, 27)
+
+// TestWriterPosix by writing and flushing many times. The output buffer
+// must contain the clearCursor and clearLine sequences.
+func TestWriterPosix(t *testing.T) {
+	out := new(bytes.Buffer)
+	w := cwriter.New(out)
+
+	testCases := []struct {
+		input, expectedOutput string
+	}{
+		{input: "foo\n", expectedOutput: "foo\n"},
+		{input: "bar\n", expectedOutput: "foo\n" + clearSequence + "bar\n"},
+		{input: "fizz\n", expectedOutput: "foo\n" + clearSequence + "bar\n" + clearSequence + "fizz\n"},
+	}
+	for _, testCase := range testCases {
+		w.Write([]byte(testCase.input))
+		w.Flush()
+		output := out.String()
+		if output != testCase.expectedOutput {
+			t.Fatalf("want %q, got %q", testCase.expectedOutput, output)
+		}
+	}
+}