Add test for binary fragment header parsing

gitdiff/parser_binary_test.go

@@ -2,6 +2,7 @@ package gitdiff
 
 import (
 	"io"
+	"reflect"
 	"testing"
 )
 
@@ -35,7 +36,7 @@ func TestParseBinaryMarker(t *testing.T) {
 
 			isBinary, hasData, err := p.ParseBinaryMarker()
 			if test.Err {
-				if err != nil || err == io.EOF {
+				if err == nil || err == io.EOF {
 					t.Fatalf("expected error parsing binary marker, but got %v", err)
 				}
 				return
@@ -52,3 +53,58 @@ func TestParseBinaryMarker(t *testing.T) {
 		})
 	}
 }
+
+func TestParseBinaryFragmentHeader(t *testing.T) {
+	tests := map[string]struct {
+		Input  string
+		Output *BinaryFragment
+		Err    bool
+	}{
+		"delta": {
+			Input: "delta 1234\n",
+			Output: &BinaryFragment{
+				Method: BinaryPatchDelta,
+				Size:   1234,
+			},
+		},
+		"literal": {
+			Input: "literal 1234\n",
+			Output: &BinaryFragment{
+				Method: BinaryPatchLiteral,
+				Size:   1234,
+			},
+		},
+		"unknownMethod": {
+			Input:  "compressed 1234\n",
+			Output: nil,
+		},
+		"notAHeader": {
+			Input:  "Binary files differ\n",
+			Output: nil,
+		},
+		"invalidSize": {
+			Input: "delta 123abc\n",
+			Err:   true,
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			p := newTestParser(test.Input, true)
+
+			frag, err := p.ParseBinaryFragmentHeader()
+			if test.Err {
+				if err == nil || err == io.EOF {
+					t.Fatalf("expected error parsing binary header, but got %v", err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error parsing binary header: %v", err)
+			}
+			if !reflect.DeepEqual(test.Output, frag) {
+				t.Errorf("incorrect binary fragment\nexpected: %+v\n  actual: %+v", test.Output, frag)
+			}
+		})
+	}
+}