ref: 3ce59c3248dec0eb0f918c42f37f53bc2ac20425
dir: /diff/lines/diff_test.go/
package lines_test
import (
"bytes"
"strconv"
"strings"
"testing"
"codeberg.org/lindenii/furgit/diff/lines"
)
func TestDiff(t *testing.T) { //nolint:maintidx
t.Parallel()
tests := []struct {
name string
oldInput string
newInput string
expected []lines.Chunk
}{
{
name: "empty inputs produce no chunks",
oldInput: "",
newInput: "",
expected: []lines.Chunk{},
},
{
name: "only additions",
oldInput: "",
newInput: "alpha\nbeta\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindAdded, Data: []byte("alpha\nbeta\n")},
},
},
{
name: "only deletions",
oldInput: "alpha\nbeta\n",
newInput: "",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("alpha\nbeta\n")},
},
},
{
name: "unchanged content is grouped",
oldInput: "same\nlines\n",
newInput: "same\nlines\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("same\nlines\n")},
},
},
{
name: "insertion in the middle",
oldInput: "a\nb\nc\n",
newInput: "a\nb\nX\nc\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("a\nb\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("X\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("c\n")},
},
},
{
name: "replacement without trailing newline",
oldInput: "first\nsecond",
newInput: "first\nsecond\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("first\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("second")},
{Kind: lines.ChunkKindAdded, Data: []byte("second\n")},
},
},
{
name: "line replacement",
oldInput: "a\nb\nc\n",
newInput: "a\nB\nc\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("a\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("b\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("B\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("c\n")},
},
},
{
name: "swap adjacent lines",
oldInput: "A\nB\n",
newInput: "B\nA\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("A\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("B\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("A\n")},
},
},
{
name: "indentation change is a full line replacement",
oldInput: "func main() {\n\treturn\n}\n",
newInput: "func main() {\n return\n}\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("func main() {\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("\treturn\n")},
{Kind: lines.ChunkKindAdded, Data: []byte(" return\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("}\n")},
},
},
{
name: "commenting out lines",
oldInput: "code\n",
newInput: "// code\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("code\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("// code\n")},
},
},
{
name: "reducing repeating lines",
oldInput: "log\nlog\nlog\n",
newInput: "log\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("log\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("log\nlog\n")},
},
},
{
name: "expanding repeating lines",
oldInput: "tick\n",
newInput: "tick\ntick\ntick\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("tick\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("tick\ntick\n")},
},
},
{
name: "interleaved modifications",
oldInput: "keep\nchange\nkeep\nchange\n",
newInput: "keep\nfixed\nkeep\nfixed\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("keep\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("change\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("fixed\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("keep\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("change\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("fixed\n")},
},
},
{
name: "large common header and footer",
oldInput: "header\nheader\nheader\nOLD\nfooter\nfooter\n",
newInput: "header\nheader\nheader\nNEW\nfooter\nfooter\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("header\nheader\nheader\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("OLD\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("NEW\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("footer\nfooter\n")},
},
},
{
name: "completely different content",
oldInput: "apple\nbanana\n",
newInput: "cherry\ndate\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("apple\nbanana\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("cherry\ndate\n")},
},
},
{
name: "unicode and emoji changes",
oldInput: "Hello 🌍\nYay\n",
newInput: "Hello 🌎\nYay\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("Hello 🌍\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("Hello 🌎\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("Yay\n")},
},
},
{
name: "binary data with embedded newlines",
oldInput: "\x00\x01\n\x02\x03\n",
newInput: "\x00\x01\n\x02\xFF\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("\x00\x01\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("\x02\x03\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("\x02\xFF\n")},
},
},
{
name: "adding trailing newline to last line",
oldInput: "Line 1\nLine 2",
newInput: "Line 1\nLine 2\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("Line 1\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("Line 2")},
{Kind: lines.ChunkKindAdded, Data: []byte("Line 2\n")},
},
},
{
name: "removing trailing newline",
oldInput: "A\nB\n",
newInput: "A\nB",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("A\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("B\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("B")},
},
},
{
name: "inserting blank lines",
oldInput: "A\nB\n",
newInput: "A\n\n\nB\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("A\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("\n\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("B\n")},
},
},
{
name: "collapsing blank lines",
oldInput: "A\n\n\n\nB\n",
newInput: "A\nB\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("A\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("\n\n\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("B\n")},
},
},
{
name: "case sensitivity check",
oldInput: "FOO\nbar\n",
newInput: "foo\nbar\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("FOO\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("foo\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("bar\n")},
},
},
{
name: "partial line match is full mismatch",
oldInput: "The quick brown fox\n",
newInput: "The quick brown fox jumps\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindDeleted, Data: []byte("The quick brown fox\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("The quick brown fox jumps\n")},
},
},
{
name: "inserting middle content",
oldInput: "Top\nBottom\n",
newInput: "Top\nMiddle\nBottom\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("Top\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("Middle\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("Bottom\n")},
},
},
{
name: "block move simulated",
oldInput: "BlockA\nBlockB\nBlockC\n",
newInput: "BlockA\nBlockC\nBlockB\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("BlockA\n")},
{Kind: lines.ChunkKindDeleted, Data: []byte("BlockB\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("BlockC\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("BlockB\n")},
},
},
{
name: "alternating additions",
oldInput: "A\nB\nC\n",
newInput: "A\n1\nB\n2\nC\n",
expected: []lines.Chunk{
{Kind: lines.ChunkKindUnchanged, Data: []byte("A\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("1\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("B\n")},
{Kind: lines.ChunkKindAdded, Data: []byte("2\n")},
{Kind: lines.ChunkKindUnchanged, Data: []byte("C\n")},
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
t.Parallel()
chunks, err := lines.Diff([]byte(tt.oldInput), []byte(tt.newInput))
if err != nil {
t.Fatalf("Diff returned error: %v", err)
}
if len(chunks) != len(tt.expected) {
t.Fatalf("expected %d chunks, got %d: %s", len(tt.expected), len(chunks), formatChunks(chunks))
}
for i := range tt.expected {
if chunks[i].Kind != tt.expected[i].Kind {
t.Fatalf("chunk %d kind mismatch: got %v, want %v; chunks: %s", i, chunks[i].Kind, tt.expected[i].Kind, formatChunks(chunks))
}
if !bytes.Equal(chunks[i].Data, tt.expected[i].Data) {
t.Fatalf("chunk %d data mismatch: got %q, want %q; chunks: %s", i, string(chunks[i].Data), string(tt.expected[i].Data), formatChunks(chunks))
}
}
})
}
}
func formatChunks(chunks []lines.Chunk) string {
var b strings.Builder
b.WriteByte('[')
for i, chunk := range chunks {
if i > 0 {
b.WriteString(", ")
}
b.WriteString(chunkKindName(chunk.Kind))
b.WriteByte(':')
b.WriteString(strconv.Quote(string(chunk.Data)))
}
b.WriteByte(']')
return b.String()
}
func chunkKindName(kind lines.ChunkKind) string {
switch kind {
case lines.ChunkKindUnchanged:
return "U"
case lines.ChunkKindDeleted:
return "D"
case lines.ChunkKindAdded:
return "A"
default:
return "?"
}
}