Merge pull request #2 from jeffallen/moreTesting

More testing

.gitignore

@@ -1,2 +1,3 @@
 *~
-cmd/remote-archive-ls/remote-archive-ls
+cmd/remote-archive-ls/remote-archive-ls*
+.vscode

README.md

@@ -3,3 +3,5 @@ seekinghttp
 
 An implementation of io.ReaderAt that works via GET and the Range header.
 
+This was discussed in an article for [Gopher Academy](https://blog.gopheracademy.com/advent-2017/seekable-http/) in 2017.
+

cmd/remote-archive-ls/main.go

@@ -86,7 +86,7 @@ func main() {
 		}
 
 		for _, f := range z.File {
-			logger.Infof("File: %s", f.FileHeader.Name)
+			fmt.Println(f.FileHeader.Name)
 		}
 		return
 	}

seekinghttp.go

@@ -86,9 +86,13 @@ func (s *SeekingHTTP) ReadAt(buf []byte, off int64) (n int, err error) {
 		s.Logger.Debugf("ReadAt len %v off %v", len(buf), off)
 	}
 
+	if off < 0 {
+		return 0, io.EOF
+	}
+
 	if s.last != nil && off > s.lastOffset {
 		end := off + int64(len(buf))
-		if end < s.lastOffset+int64(s.last.Len()) {
+		if end <= s.lastOffset+int64(s.last.Len()) {
 			start := off - s.lastOffset
 			if s.Logger != nil {
 				s.Logger.Debugf("cache hit: range (%v-%v) is within cache (%v-%v)", off, off+int64(len(buf)), s.lastOffset, s.lastOffset+int64(s.last.Len()))
@@ -111,8 +115,12 @@ func (s *SeekingHTTP) ReadAt(buf []byte, off int64) (n int, err error) {
 		return 0, err
 	}
 
-	// Fetch more than what they asked for to reduce round-trips
-	wanted := 10 * len(buf)
+	// Minimum fetch size is 1 meg
+	wanted := 1024 * 1024
+	if wanted < len(buf) {
+		wanted = len(buf)
+	}
+
 	rng := fmtRange(off, int64(wanted))
 	req.Header.Add("Range", rng)
 
@@ -154,6 +162,9 @@ func (s *SeekingHTTP) ReadAt(buf []byte, off int64) (n int, err error) {
 		if err != nil {
 			return 0, err
 		}
+		if s.Logger != nil {
+			s.Logger.Debugf("loaded %d bytes into last", s.last.Len())
+		}
 
 		s.lastOffset = off
 		var n int

seekinghttp_test.go

@@ -2,29 +2,61 @@ package seekinghttp
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"net/http"
+	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
+type logger struct {
+	t *testing.T
+}
+
+func (l logger) Infof(format string, args ...interface{}) {
+	l.t.Logf(fmt.Sprintf("[INFO] %s", format), args...)
+}
+func (l logger) Debugf(format string, args ...interface{}) {
+	l.t.Logf(fmt.Sprintf("[DEBUG] %s", format), args...)
+}
+
 // MockHTTPClient is a mock implementation of the http.Client interface for testing purposes.
-type MockHTTPClient struct{}
+type MockHTTPClient struct {
+	str    string
+	numReq int
+}
+
+func (c *MockHTTPClient) Do(req *http.Request) (*http.Response, error) {
+	x := strings.Split(req.Header["Range"][0], "=")
+	y := strings.Split(x[1], "-")
+	start, _ := strconv.Atoi(y[0])
+	end, _ := strconv.Atoi(y[1])
+
+	if end > len(c.str) {
+		end = len(c.str)
+	}
+	if start > end {
+		start = end
+	}
 
-func (c *MockHTTPClient) Do(_ *http.Request) (*http.Response, error) {
 	// Create a mock response for testing purposes.
 	resp := &http.Response{
 		StatusCode: http.StatusOK,
-		Body:       io.NopCloser(bytes.NewReader([]byte("Mock HTTP response body"))),
+		Body:       io.NopCloser(bytes.NewReader([]byte(c.str[start:end]))),
 	}
+	c.numReq++
 	return resp, nil
 }
 
 func TestReadAt(t *testing.T) {
 	// Create a new SeekingHTTP instance with a mock HTTP client.
 	s := New("https://example.com")
-	s.Client = &MockHTTPClient{}
+	m := &MockHTTPClient{str: "Mock HTTP response body"}
+	s.Client = m
+	s.Logger = &logger{t: t}
 
 	// Define test cases.
 	testCases := []struct {
@@ -35,14 +67,55 @@ func TestReadAt(t *testing.T) {
 	}{
 		{0, 10, 10, nil},
 		{10, 1, 1, nil},
-		{30, 30, 23, nil},
+		{30, 30, 0, nil},
+		{-1, 0, 0, io.EOF},
 	}
 
 	for _, tc := range testCases {
 		buf := make([]byte, tc.bufSize)
 		n, err := s.ReadAt(buf, tc.offset)
 
-		assert.ErrorIs(t, err, tc.expectErr, "ReadAt(offset=%d, bufSize=%d) error = %v, expected error = %v", tc.offset, tc.bufSize, err, tc.expectErr)
-		assert.Equal(t, n, tc.expectLen, "ReadAt(offset=%d, bufSize=%d) len = %d, expected len = %d", tc.offset, tc.bufSize, n, tc.expectLen)
+		assert.ErrorIs(t, tc.expectErr, err, "ReadAt(offset=%d, bufSize=%d) error = %v, expected error = %v", tc.offset, tc.bufSize, err, tc.expectErr)
+		assert.Equal(t, tc.expectLen, n, "ReadAt(offset=%d, bufSize=%d) len = %d, expected len = %d", tc.offset, tc.bufSize, n, tc.expectLen)
 	}
+	// expect 2 reads: one to load the cache, and one to look for bytes past the end for the seek to 30.
+	assert.Equal(t, 2, m.numReq)
+}
+
+func TestReadNothing(t *testing.T) {
+	// Create a new SeekingHTTP instance with a mock HTTP client.
+	s := New("https://example.com")
+	s.Client = &MockHTTPClient{str: ""}
+	s.Logger = &logger{t: t}
+
+	buf := make([]byte, 10)
+	n, err := s.Read(buf)
+	assert.ErrorIs(t, err, nil)
+	assert.Equal(t, 0, n)
+}
+
+func TestReadOffEnd(t *testing.T) {
+	// Create a new SeekingHTTP instance with a mock HTTP client.
+	s := New("https://example.com")
+	s.Client = &MockHTTPClient{str: "0123456789abcdefghij"}
+	s.Logger = &logger{t: t}
+
+	buf := make([]byte, 10)
+	n, err := s.Read(buf)
+	assert.ErrorIs(t, err, nil)
+	assert.Equal(t, n, len(buf))
+	assert.Equal(t, "0123456789", string(buf))
+	assert.Equal(t, int64(10), s.offset)
+
+	n, err = s.Read(buf)
+	assert.ErrorIs(t, err, nil)
+	assert.Equal(t, n, len(buf))
+	assert.Equal(t, "abcdefghij", string(buf))
+	assert.Equal(t, int64(20), s.offset)
+
+	n, err = s.Read(buf)
+	assert.ErrorIs(t, err, nil)
+	assert.Equal(t, 0, n)
+	assert.Equal(t, int64(20), s.offset)
+
 }