Support Stringer for Lines iters

Author: BooleanCat

iter/lines.go

@@ -49,13 +49,21 @@ func (iter *LinesIter) Next() option.Option[result.Result[[]byte]] {
 	return option.Some(result.Ok(bytes.TrimRight(content, "\r\n")))
 }
 
+// String implements the [fmt.Stringer] interface
+func (iter LinesIter) String() string {
+	return "Iterator<Lines, type=Result<[]byte>>"
+}
+
 // CollectResults is a convenience method for [CollectResults], providing this
 // iterator as an argument.
 func (iter *LinesIter) CollectResults() result.Result[[][]byte] {
 	return CollectResults[[]byte](iter)
 }
 
-var _ Iterator[result.Result[[]byte]] = new(LinesIter)
+var (
+	_ fmt.Stringer                    = new(LinesIter)
+	_ Iterator[result.Result[[]byte]] = new(LinesIter)
+)
 
 type LinesStringIter struct {
 	BaseIter[result.Result[string]]
@@ -75,6 +83,11 @@ func (iter *LinesStringIter) Next() option.Option[result.Result[string]] {
 	}
 }
 
+// String implements the [fmt.Stringer] interface
+func (iter LinesStringIter) String() string {
+	return "Iterator<LinesString, type=Result<string>>"
+}
+
 // CollectResults is a convenience method for [CollectResults], providing this
 // iterator as an argument.
 func (iter *LinesStringIter) CollectResults() result.Result[[]string] {
@@ -89,4 +102,7 @@ func LinesString(r io.Reader) *LinesStringIter {
 	return iter
 }
 
-var _ Iterator[result.Result[string]] = new(LinesStringIter)
+var (
+	_ fmt.Stringer                    = new(LinesStringIter)
+	_ Iterator[result.Result[string]] = new(LinesStringIter)
+)

iter/lines_test.go

@@ -22,6 +22,11 @@ func ExampleLinesString() {
 	// Output: [hello there]
 }
 
+func ExampleLinesStringIter_String() {
+	fmt.Println(iter.LinesString(bytes.NewBufferString("hello\nthere")))
+	// Output: Iterator<LinesString, type=Result<string>>
+}
+
 func ExampleLines() {
 	lines := iter.Lines(bytes.NewBufferString("hello\nthere"))
 	unwrapped := iter.Map[result.Result[[]byte]](lines, ops.UnwrapResult[[]byte])
@@ -30,6 +35,11 @@ func ExampleLines() {
 	// Output: [[104 101 108 108 111] [116 104 101 114 101]]
 }
 
+func ExampleLinesIter_String() {
+	fmt.Println(iter.Lines(bytes.NewBufferString("hello\nthere")))
+	// Output: Iterator<Lines, type=Result<[]byte>>
+}
+
 func TestLines(t *testing.T) {
 	file, err := os.Open("fixtures/lines.txt")
 	assert.Nil(t, err)
@@ -92,6 +102,14 @@ func TestLinesCollectResults(t *testing.T) {
 	assert.Empty[byte](t, lines[4])
 }
 
+func TestLinesIter_String(t *testing.T) {
+	lines := iter.Lines(new(bytes.Buffer))
+	expected := "Iterator<Lines, type=Result<[]byte>>"
+
+	assert.Equal(t, fmt.Sprintf("%s", lines), expected)  //nolint:gosimple
+	assert.Equal(t, fmt.Sprintf("%s", *lines), expected) //nolint:gosimple
+}
+
 func TestLinesString(t *testing.T) {
 	file, err := os.Open("fixtures/lines.txt")
 	assert.Nil(t, err)
@@ -154,3 +172,11 @@ func TestLinesStringCollectResults(t *testing.T) {
 		[]string{"This is", "a file", "with", "a trailing newline", ""},
 	)
 }
+
+func TestLinesStringIter_String(t *testing.T) {
+	lines := iter.LinesString(new(bytes.Buffer))
+	expected := "Iterator<LinesString, type=Result<string>>"
+
+	assert.Equal(t, fmt.Sprintf("%s", lines), expected)  //nolint:gosimple
+	assert.Equal(t, fmt.Sprintf("%s", *lines), expected) //nolint:gosimple
+}