From 739668281be0cb3575b5abdbb001ce2ddf96d439 Mon Sep 17 00:00:00 2001
From: Taylor Blau <me@ttaylorr.com>
Date: Thu, 16 Feb 2017 20:13:07 -0700
Subject: [PATCH] progress/copycallback: test underfilled buffers

---
 progress/copycallback_test.go | 47 +++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 progress/copycallback_test.go

diff --git a/progress/copycallback_test.go b/progress/copycallback_test.go
new file mode 100644
index 00000000..12814662
--- /dev/null
+++ b/progress/copycallback_test.go
@@ -0,0 +1,47 @@
+package progress
+
+import (
+	"bytes"
+	"sync/atomic"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCopyCallbackReaderCallsCallbackUnderfilledBuffer(t *testing.T) {
+	var (
+		calls               uint32
+		actualTotalSize     int64
+		actualReadSoFar     int64
+		actualReadSinceLast int
+	)
+
+	cb := func(totalSize int64, readSoFar int64, readSinceLast int) error {
+		atomic.AddUint32(&calls, 1)
+
+		actualTotalSize = totalSize
+		actualReadSoFar = readSoFar
+		actualReadSinceLast = readSinceLast
+
+		return nil
+	}
+
+	buf := []byte{0x1}
+	r := &CallbackReader{
+		C:         cb,
+		TotalSize: 3,
+		ReadSize:  2,
+		Reader:    bytes.NewReader(buf),
+	}
+
+	p := make([]byte, len(buf)+1)
+	n, err := r.Read(p)
+
+	assert.Equal(t, 1, n)
+	assert.Nil(t, err)
+
+	assert.EqualValues(t, 1, calls)
+	assert.EqualValues(t, 3, actualTotalSize)
+	assert.EqualValues(t, 2+1, actualReadSoFar)
+	assert.EqualValues(t, 1, actualReadSinceLast)
+}