container/mts: wrote test for BytesForMetaInterval and corrected bugs

container/mts/payload.go

@@ -186,46 +186,28 @@ var (
 
 func (c *Clip) BytesForMetaInterval(key, from, to string) ([]byte, error) {
 	// First check that the interval makes sense.
-	if from >= to {
+	if from == to {
 		return nil, errMetaRange
 	}
 
-	// Use binary search to find 'from'.
-	n := len(c.frames)
-	idx := sort.Search(
-		n,
-		func(i int) bool {
-			if c.frames[i].Meta[key] == from {
-				return true
+	var start, end int
+
+	// Try and find from.
+	for i := 0; i < len(c.frames); i++ {
+		f := c.frames[i]
+		if f.Meta[key] == from {
+			start = f.idx
+
+			// Now try and find to.
+			for ; i < len(c.frames); i++ {
+				f = c.frames[i]
+				if f.Meta[key] == to {
+					end = f.idx
+					return c.backing[start : end+len(f.Media)], nil
+				}
 			}
-			return false
-		},
-	)
-	if idx == n {
-		return nil, errMetaLowerBound
+			return nil, errMetaUpperBound
+		}
 	}
-
-	// Now get the start index for the backing slice from this Frame.
-	start := c.frames[idx].idx
-
-	// Now use binary search again to find 'to'.
-	off := idx + 1
-	n = n - (off)
-	idx = sort.Search(
-		n,
-		func(i int) bool {
-			if c.frames[i+off].Meta[key] == to {
-				return true
-			}
-			return false
-		},
-	)
-	if idx == n {
-		return nil, errMetaUpperBound
-	}
-
-	// Now get the end index for the backing slice from this Frame, and return
-	// segment from backing slice corresponding to start and end.
-	end := c.frames[idx+off].idx
-	return c.backing[start : end+len(c.frames[idx+off].Media)], nil
+	return nil, errMetaLowerBound
 }

container/mts/payload_test.go

@@ -302,16 +302,98 @@ func TestBytesForPTSInterval(t *testing.T) {
 
 		// First check the error.
 		if err != nil && err != test.err {
-			t.Errorf("unexpected error: %v for test: %v from BytesForPTSInterval", err, i)
+			t.Errorf("unexpected error: %v for test: %v", err, i)
 			continue
 		} else if err != test.err {
-			t.Errorf("expected to get error: %v for test: %v from BytesForPTSInterval", test.err, i)
+			t.Errorf("expected to get error: %v for test: %v", test.err, i)
 			continue
 		}
 
 		// Now check data.
 		if test.err == nil && !bytes.Equal(test.expect, got) {
-			t.Errorf("did not get expected data for test: %v from BytesForPTSInterval.\n Got: %v\n, Want: %v\n", i, got, test.expect)
+			t.Errorf("did not get expected data for test: %v\n Got: %v\n, Want: %v\n", i, got, test.expect)
+		}
+	}
+}
+
+func TestBytesForMetaInterval(t *testing.T) {
+	const (
+		numOfTestFrames = 10
+		ptsInterval     = 4
+		frameSize       = 3
+		key             = "n"
+	)
+
+	clip := &Clip{}
+
+	// Generate test frames.
+	for i := 0; i < numOfTestFrames; i++ {
+		clip.backing = append(clip.backing, []byte{byte(i), byte(i), byte(i)}...)
+		clip.frames = append(
+			clip.frames,
+			Frame{
+				Media: clip.backing[i*frameSize : (i+1)*frameSize],
+				idx:   i * frameSize,
+				Meta: map[string]string{
+					key: strconv.Itoa(i),
+				},
+			},
+		)
+	}
+
+	// We test each of these scenarios.
+	tests := []struct {
+		from   string
+		to     string
+		expect []byte
+		err    error
+	}{
+		{
+			from: "1",
+			to:   "3",
+			expect: []byte{
+				0x01, 0x01, 0x01,
+				0x02, 0x02, 0x02,
+				0x03, 0x03, 0x03,
+			},
+			err: nil,
+		},
+		{
+			from:   "1",
+			to:     "1",
+			expect: nil,
+			err:    errMetaRange,
+		},
+		{
+			from:   "20",
+			to:     "1",
+			expect: nil,
+			err:    errMetaLowerBound,
+		},
+		{
+			from:   "1",
+			to:     "20",
+			expect: nil,
+			err:    errMetaUpperBound,
+		},
+	}
+
+	// Run tests.
+	for i, test := range tests {
+		got, err := clip.BytesForMetaInterval(key, test.from, test.to)
+
+		// First check the error.
+		if err != nil && err != test.err {
+			t.Errorf("unexpected error: %v for test: %v", err, i)
+			continue
+		} else if err != test.err {
+			t.Errorf("expected to get error: %v for test: %v", test.err, i)
+			continue
+		}
+
+		// Now check data.
+		if test.err == nil && !bytes.Equal(test.expect, got) {
+			t.Errorf("did not get expected data for test: %v\n Got: %v\n, Want: %v\n", i, got, test.expect)
 		}
 	}
 }