Function TestCopyLinesFrom

pkg/gitdiff/io_test.go:210–254

(t *testing.T)

}

func TestCopyLinesFrom(t *testing.T) {
	tests := map[string]struct {
		Lines  int64
		Offset int64
	}{
		"copyAll": {
			Lines: lineBufferSize / 2,
		},
		"copyPartial": {
			Lines:  lineBufferSize / 2,
			Offset: lineBufferSize / 4,
		},
		"copyLarge": {
			Lines: 8 * lineBufferSize,
		},
	}

	const lineLength = 128

	for name, test := range tests {
		t.Run(name, func(t *testing.T) {
			data := make([]byte, test.Lines*lineLength)
			for i := range data {
				data[i] = byte(32 + rand.Intn(95)) // ascii letters, numbers, symbols
				if i%lineLength == lineLength-1 {
					data[i] = '\n'
				}
			}

			var dst bytes.Buffer
			n, err := copyLinesFrom(&dst, &lineReaderAt{r: bytes.NewReader(data)}, test.Offset)
			if err != nil {
				t.Fatalf("unexpected error copying data: %v", err)
			}
			if n != test.Lines-test.Offset {
				t.Fatalf("incorrect number of lines copied: expected %d, actual %d", test.Lines-test.Offset, n)
			}

			expected := data[test.Offset*lineLength:]
			if !bytes.Equal(expected, dst.Bytes()) {
				t.Fatalf("incorrect data copied:\nexpected: %v\nactual: %v", expected, dst.Bytes())
			}
		})
	}
}