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bytes: restore old Trim/TrimLeft behavior for nil

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Keep returning nil for the cases where we historically returned nil,
even though this is slightly different for TrimLeft and TrimRight.

Fixes #51793

Change-Id: Ifbdfc6b09d52b8e063cfe6341019f9b2eb8b70e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/393876
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Ian Lance Taylor 2022-03-18 12:14:20 -07:00
parent 460fd63ccc
commit 32fdad19a2
2 changed files with 106 additions and 11 deletions
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93
src/bytes/bytes_test.go
View file

@ -1278,24 +1278,69 @@ var trimTests = []TrimTest{
{"TrimSuffix", "aabb", "b", "aab"},
}
type TrimNilTest struct {
f string
in []byte
arg string
out []byte
}
var trimNilTests = []TrimNilTest{
{"Trim", nil, "", nil},
{"Trim", []byte{}, "", nil},
{"Trim", []byte{'a'}, "a", nil},
{"Trim", []byte{'a', 'a'}, "a", nil},
{"Trim", []byte{'a'}, "ab", nil},
{"Trim", []byte{'a', 'b'}, "ab", nil},
{"Trim", []byte("☺"), "☺", nil},
{"TrimLeft", nil, "", nil},
{"TrimLeft", []byte{}, "", nil},
{"TrimLeft", []byte{'a'}, "a", nil},
{"TrimLeft", []byte{'a', 'a'}, "a", nil},
{"TrimLeft", []byte{'a'}, "ab", nil},
{"TrimLeft", []byte{'a', 'b'}, "ab", nil},
{"TrimLeft", []byte("☺"), "☺", nil},
{"TrimRight", nil, "", nil},
{"TrimRight", []byte{}, "", []byte{}},
{"TrimRight", []byte{'a'}, "a", []byte{}},
{"TrimRight", []byte{'a', 'a'}, "a", []byte{}},
{"TrimRight", []byte{'a'}, "ab", []byte{}},
{"TrimRight", []byte{'a', 'b'}, "ab", []byte{}},
{"TrimRight", []byte("☺"), "☺", []byte{}},
{"TrimPrefix", nil, "", nil},
{"TrimPrefix", []byte{}, "", []byte{}},
{"TrimPrefix", []byte{'a'}, "a", []byte{}},
{"TrimPrefix", []byte("☺"), "☺", []byte{}},
{"TrimSuffix", nil, "", nil},
{"TrimSuffix", []byte{}, "", []byte{}},
{"TrimSuffix", []byte{'a'}, "a", []byte{}},
{"TrimSuffix", []byte("☺"), "☺", []byte{}},
}
func TestTrim(t *testing.T) {
for _, tc := range trimTests {
name := tc.f
var f func([]byte, string) []byte
var fb func([]byte, []byte) []byte
toFn := func(name string) (func([]byte, string) []byte, func([]byte, []byte) []byte) {
switch name {
case "Trim":
f = Trim
return Trim, nil
case "TrimLeft":
f = TrimLeft
return TrimLeft, nil
case "TrimRight":
f = TrimRight
return TrimRight, nil
case "TrimPrefix":
fb = TrimPrefix
return nil, TrimPrefix
case "TrimSuffix":
fb = TrimSuffix
return nil, TrimSuffix
default:
t.Errorf("Undefined trim function %s", name)
return nil, nil
}
}
for _, tc := range trimTests {
name := tc.f
f, fb := toFn(name)
if f == nil && fb == nil {
continue
}
var actual string
if f != nil {
@ -1307,6 +1352,36 @@ func TestTrim(t *testing.T) {
t.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.arg, actual, tc.out)
}
}
for _, tc := range trimNilTests {
name := tc.f
f, fb := toFn(name)
if f == nil && fb == nil {
continue
}
var actual []byte
if f != nil {
actual = f(tc.in, tc.arg)
} else {
actual = fb(tc.in, []byte(tc.arg))
}
report := func(s []byte) string {
if s == nil {
return "nil"
} else {
return fmt.Sprintf("%q", s)
}
}
if len(actual) != 0 {
t.Errorf("%s(%s, %q) returned non-empty value", name, report(tc.in), tc.arg)
} else {
actualNil := actual == nil
outNil := tc.out == nil
if actualNil != outNil {
t.Errorf("%s(%s, %q) got nil %t; want nil %t", name, report(tc.in), tc.arg, actualNil, outNil)
}
}
}
}
type predicate struct {