add more fuzzing

card_test.go

@@ -391,13 +391,58 @@ func TestCard_Revision(t *testing.T) {
 }
 
 func TestCard_FieldValue(t *testing.T) {
-	got := NewFieldValue("geo:1.23,4.56")
-	if expected := FieldValue("geo:1.23\\,4.56"); got != expected {
-		t.Errorf("Expected FieldValue to be %q but got %q", expected, got)
+	fieldValues := map[FieldValue][]string{
+		"":                  {""},
+		",":                 {"", ""},
+		"\\,":               {","},
+		",,\\,,":            {"", "", ",", ""},
+		"geo:1.23\\,4.56":   {"geo:1.23,4.56"},
+		"geo:1.23,4.56":     {"geo:1.23", "4.56"},
+		"geo:1\\,23,4\\,56": {"geo:1,23", "4,56"},
+	}
+	for fv, parts := range fieldValues {
+		t.Run(fv.String(), func(t *testing.T) {
+			gotParts := fv.Values()
+			if !reflect.DeepEqual(parts, gotParts) {
+				t.Errorf("Expected parts to be %+v but got %+v", parts, gotParts)
+			}
+
+			gotFV := NewFieldValue(parts...)
+			if gotFV != fv {
+				t.Errorf("Expected FieldValue to be %+v but got %+v", fv, gotFV)
+			}
+		})
 	}
 }
 
-func FuzzCard_FieldValue(f *testing.F) {
+// go test -fuzztime=10s -fuzz=Card_FieldValueRaw
+func FuzzCard_FieldValueRaw(f *testing.F) {
+	f.Add(``)
+	f.Add(`123`)
+	f.Add(`1,2,3`)
+	f.Add(`1\abc`) // missing escaping of "\"
+	f.Add(`1\,2,3`)
+	f.Add(`1\\,2,3`)
+	f.Fuzz(func(t *testing.T, raw string) {
+		fv := FieldValue(raw)
+		parts := fv.Values()
+		got1 := NewFieldValue(parts...)
+		if got1 != fv {
+			// the raw value was wrongly escaped:
+			// "got" should now be correctly escaped
+			if len(got1) <= len(fv) {
+				t.Errorf("Expected a larger (escaped) string than %q, got %q", fv, got1)
+			}
+			// encode again and check that we get back the same (correctly escaped) raw value
+			got2 := NewFieldValue(got1.Values()...)
+			if got1 != got2 {
+				t.Errorf("Expected %q, got %q", got1, got2)
+			}
+		}
+	})
+}
+
+func FuzzCard_FieldValueParts(f *testing.F) {
 	f.Add("p0", "p1")
 	f.Add("1,2", "3")
 	f.Add("1\\,2", "3")