From cdb48a8970d1e766c184635497d2188273d7649d Mon Sep 17 00:00:00 2001
From: Toby Burress <kurin@google.com>
Date: Thu, 22 Feb 2018 01:14:04 +0000
Subject: [PATCH] Add tests for the eager-header refactor.

---
 internal/pack/pack_internal_test.go | 54 +++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/internal/pack/pack_internal_test.go b/internal/pack/pack_internal_test.go
index bd790609f..6694b7333 100644
--- a/internal/pack/pack_internal_test.go
+++ b/internal/pack/pack_internal_test.go
@@ -22,8 +22,8 @@ func (rd *countingReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
 
 func TestReadHeaderEagerLoad(t *testing.T) {
 
-	testReadHeader := func(dataSize int, entryCount uint, expectedReadInvocationCount int) {
-		expectedHeader := rtest.Random(0, int(entryCount*entrySize)+crypto.Extension)
+	testReadHeader := func(dataSize, entryCount, expectedReadInvocationCount int) {
+		expectedHeader := rtest.Random(0, entryCount*int(entrySize)+crypto.Extension)
 
 		buf := &bytes.Buffer{}
 		buf.Write(rtest.Random(0, dataSize))                                // pack blobs data
@@ -58,3 +58,53 @@ func TestReadHeaderEagerLoad(t *testing.T) {
 	testReadHeader(dataSize+3, 1, 1)
 	testReadHeader(dataSize+4, 1, 1)
 }
+
+func TestReadRecords(t *testing.T) {
+	testReadRecords := func(dataSize, entryCount, totalRecords int) {
+		totalHeader := rtest.Random(0, totalRecords*int(entrySize)+crypto.Extension)
+		off := len(totalHeader) - (entryCount*int(entrySize) + crypto.Extension)
+		if off < 0 {
+			off = 0
+		}
+		expectedHeader := totalHeader[off:]
+
+		buf := &bytes.Buffer{}
+		buf.Write(rtest.Random(0, dataSize))                             // pack blobs data
+		buf.Write(totalHeader)                                           // pack header
+		binary.Write(buf, binary.LittleEndian, uint32(len(totalHeader))) // pack header length
+
+		rd := bytes.NewReader(buf.Bytes())
+
+		header, count, err := readRecords(rd, int64(rd.Len()), entryCount)
+		rtest.OK(t, err)
+		rtest.Equals(t, expectedHeader, header)
+		rtest.Equals(t, totalRecords, count)
+	}
+
+	// basic
+	testReadRecords(100, 1, 1)
+	testReadRecords(100, 0, 1)
+	testReadRecords(100, 1, 0)
+
+	// header entries ~ eager entries
+	testReadRecords(100, eagerEntries, eagerEntries-1)
+	testReadRecords(100, eagerEntries, eagerEntries)
+	testReadRecords(100, eagerEntries, eagerEntries+1)
+
+	// file size == eager header load size
+	eagerLoadSize := int((eagerEntries * entrySize) + crypto.Extension)
+	headerSize := int(1*entrySize) + crypto.Extension
+	dataSize := eagerLoadSize - headerSize - binary.Size(uint32(0))
+	testReadRecords(dataSize-1, 1, 1)
+	testReadRecords(dataSize, 1, 1)
+	testReadRecords(dataSize+1, 1, 1)
+	testReadRecords(dataSize+2, 1, 1)
+	testReadRecords(dataSize+3, 1, 1)
+	testReadRecords(dataSize+4, 1, 1)
+
+	for i := 0; i < 2; i++ {
+		for j := 0; j < 2; j++ {
+			testReadRecords(dataSize, i, j)
+		}
+	}
+}