improve tests

Signed-off-by: Florian Lehner <[email protected]>

ematch_nbyte.go

@@ -20,7 +20,8 @@ type tcfEmNByte struct {
 
 func unmarshalNByteMatch(data []byte, info *NByteMatch) error {
 	if len(data) < 8 {
-		return fmt.Errorf("unmarshalNByteMatch: incomplete data")
+		return fmt.Errorf("unmarshalNByteMatch: incomplete data: %w",
+			ErrInvalidArg)
 	}
 
 	// We can not unmarshal elements of a non-public struct.
@@ -29,7 +30,8 @@ func unmarshalNByteMatch(data []byte, info *NByteMatch) error {
 	needleLen := binary.LittleEndian.Uint16(data[2:4])
 	info.Layer = uint8(data[4])
 	if len(data) < (8 + int(needleLen)) {
-		return fmt.Errorf("unmarshalNByteMatch: incomplete needle")
+		return fmt.Errorf("unmarshalNByteMatch: invalid needle: %w",
+			ErrInvalidArg)
 	}
 	info.Needle = data[8 : 8+needleLen]
 

ematch_nbyte_test.go

@@ -43,3 +43,37 @@ func TestNByteMatch(t *testing.T) {
 		}
 	})
 }
+
+func TestUnmarshalNByteMatch(t *testing.T) {
+	tests := map[string]struct {
+		data      []byte
+		needleLen uint16
+		err       error
+	}{
+		"invalid lenght": {
+			data: []byte{0x0, 0x1, 0x2, 0x3},
+			err:  ErrInvalidArg,
+		},
+		"invalid needle": {
+			data: []byte{0x00, 0x00,
+				0xaa, 0xaa,
+				0x01,
+				0x00, 0x00, 0x00,
+				0x0a, 0x0b, 0x0c},
+			err: ErrInvalidArg,
+		},
+	}
+
+	for name, testcase := range tests {
+		name := name
+		testcase := testcase
+		t.Run(name, func(t *testing.T) {
+			info := NByteMatch{}
+			if err := unmarshalNByteMatch(testcase.data, &info); err != nil {
+				if !errors.Is(err, ErrInvalidArg) {
+					t.Fatalf("Unexpected error: %v", err)
+				}
+			}
+		})
+	}
+}