plumbing: handle pktline erro-line as errors

Error when encountering an error-line
See https://git-scm.com/docs/pack-protocol

Update plumbing/format/pktline/error.go

Co-authored-by: Paulo Gomes <paulo.gomes.uk@gmail.com>

Update plumbing/format/pktline/error.go

Co-authored-by: Paulo Gomes <paulo.gomes.uk@gmail.com>

feat: format newline

1 files changed, 68 insertions, 0 deletions

diff --git a/plumbing/format/pktline/error_test.go b/plumbing/format/pktline/error_test.go
new file mode 100644
index 0000000..3cffd20
--- /dev/null
+++ b/plumbing/format/pktline/error_test.go
@@ -0,0 +1,68 @@
+package pktline
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"testing"
+)
+
+func TestEncodeEmptyErrorLine(t *testing.T) {
+	e := &ErrorLine{}
+	err := e.Encode(io.Discard)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestEncodeErrorLine(t *testing.T) {
+	e := &ErrorLine{
+		Text: "something",
+	}
+	var buf bytes.Buffer
+	err := e.Encode(&buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if buf.String() != "0012ERR something\n" {
+		t.Fatalf("unexpected encoded error line: %q", buf.String())
+	}
+}
+
+func TestDecodeEmptyErrorLine(t *testing.T) {
+	var buf bytes.Buffer
+	e := &ErrorLine{}
+	err := e.Decode(&buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if e.Text != "" {
+		t.Fatalf("unexpected error line: %q", e.Text)
+	}
+}
+
+func TestDecodeErrorLine(t *testing.T) {
+	var buf bytes.Buffer
+	buf.WriteString("000eERR foobar")
+	var e *ErrorLine
+	err := e.Decode(&buf)
+	if !errors.As(err, &e) {
+		t.Fatalf("expected error line, got: %T: %v", err, err)
+	}
+	if e.Text != "foobar" {
+		t.Fatalf("unexpected error line: %q", e.Text)
+	}
+}
+
+func TestDecodeErrorLineLn(t *testing.T) {
+	var buf bytes.Buffer
+	buf.WriteString("000fERR foobar\n")
+	var e *ErrorLine
+	err := e.Decode(&buf)
+	if !errors.As(err, &e) {
+		t.Fatalf("expected error line, got: %T: %v", err, err)
+	}
+	if e.Text != "foobar" {
+		t.Fatalf("unexpected error line: %q", e.Text)
+	}
+}