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unit tests with full SlogSink mock implementation
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This turns testLogSink into an implementation of SlogSink if slog is supported,
then runs through some scenarios where values get added using different APIs.
The end result gets compared by formatting with the slog JSON handler because
that is easier than writing custom code for a deep-equal comparison of slog
attributes.

The "with-group-and-logr-values" is the case which was broken.
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pohly committed Dec 4, 2023
1 parent c7d1b58 commit ffd51a4
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23 changes: 23 additions & 0 deletions logr_noslog_test.go
Original file line number Diff line number Diff line change
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//go:build !go1.21
// +build !go1.21

/*
Copyright 2023 The logr Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package logr

//nolint:unused
type testSlogSink struct{}
218 changes: 218 additions & 0 deletions logr_slog_test.go
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@@ -0,0 +1,218 @@
//go:build go1.21
// +build go1.21

/*
Copyright 2023 The logr Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package logr

import (
"bytes"
"context"
"log/slog"
"testing"
"time"
)

var _ SlogSink = &testLogSink{}

// testSlogSink gets embedded in testLogSink to add slog-specific fields
// which are only available when slog is supported by Go.
type testSlogSink struct {
attrs []slog.Attr
groups []string

fnHandle func(l *testLogSink, ctx context.Context, record slog.Record)
fnWithAttrs func(l *testLogSink, attrs []slog.Attr)
fnWithGroup func(l *testLogSink, name string)
}

func (l *testLogSink) Handle(ctx context.Context, record slog.Record) error {
if l.fnHandle != nil {
l.fnHandle(l, ctx, record)
}
return nil
}

func (l *testLogSink) WithAttrs(attrs []slog.Attr) SlogSink {
if l.fnWithAttrs != nil {
l.fnWithAttrs(l, attrs)
}
out := *l
n := len(out.attrs)
out.attrs = append(out.attrs[:n:n], attrs...)
return &out
}

func (l *testLogSink) WithGroup(name string) SlogSink {
if l.fnWithGroup != nil {
l.fnWithGroup(l, name)
}
out := *l
n := len(out.groups)
out.groups = append(out.groups[:n:n], name)
return &out
}

func withAttrs(record slog.Record, attrs ...slog.Attr) slog.Record {
record = record.Clone()
record.AddAttrs(attrs...)
return record
}

func toJSON(record slog.Record) string {
var buffer bytes.Buffer
record.Time = time.Time{}
handler := slog.NewJSONHandler(&buffer, nil)
if err := handler.Handle(context.Background(), record); err != nil {
return err.Error()
}
return buffer.String()
}

func TestToSlogHandler(t *testing.T) {
lvlThreshold := 0
actualCalledHandle := 0
var actualRecord slog.Record

sink := &testLogSink{}
logger := New(sink)

sink.fnEnabled = func(lvl int) bool {
return lvl <= lvlThreshold
}

sink.fnHandle = func(l *testLogSink, ctx context.Context, record slog.Record) {
actualCalledHandle++

// Combine attributes from sink and call. Ordering of WithValues and WithAttrs
// is wrong, but good enough for test cases.
var values slog.Record
values.Add(l.withValues...)
var attrs []any
add := func(attr slog.Attr) bool {
attrs = append(attrs, attr)
return true
}
values.Attrs(add)
record.Attrs(add)
for _, attr := range l.attrs {
attrs = append(attrs, attr)
}

// Wrap them in groups - not quite correct for WithValues that
// follows WithGroup, but good enough for test cases.
for i := len(l.groups) - 1; i >= 0; i-- {
attrs = []any{slog.Group(l.groups[i], attrs...)}
}

actualRecord = slog.Record{
Level: record.Level,
Message: record.Message,
}
actualRecord.Add(attrs...)
}

verify := func(t *testing.T, expectedRecord slog.Record) {
actual := toJSON(actualRecord)
expected := toJSON(expectedRecord)
if expected != actual {
t.Errorf("JSON dump did not match, expected:\n%s\nGot:\n%s\n", expected, actual)
}
}

reset := func() {
lvlThreshold = 0
actualCalledHandle = 0
actualRecord = slog.Record{}
}

testcases := map[string]struct {
run func()
expectedRecord slog.Record
}{
"simple": {
func() { slog.New(ToSlogHandler(logger)).Info("simple") },
slog.Record{Message: "simple"},
},

"disabled": {
func() { slog.New(ToSlogHandler(logger.V(1))).Info("") },
slog.Record{},
},

"enabled": {
func() {
lvlThreshold = 1
slog.New(ToSlogHandler(logger.V(1))).Info("enabled")
},
slog.Record{Level: -1, Message: "enabled"},
},

"error": {
func() { slog.New(ToSlogHandler(logger.V(100))).Error("error") },
slog.Record{Level: slog.LevelError, Message: "error"},
},

"with-parameters": {
func() { slog.New(ToSlogHandler(logger)).Info("", "answer", 42, "foo", "bar") },
withAttrs(slog.Record{}, slog.Int("answer", 42), slog.String("foo", "bar")),
},

"with-values": {
func() { slog.New(ToSlogHandler(logger.WithValues("answer", 42, "foo", "bar"))).Info("") },
withAttrs(slog.Record{}, slog.Int("answer", 42), slog.String("foo", "bar")),
},

"with-group": {
func() { slog.New(ToSlogHandler(logger)).WithGroup("group").Info("", "answer", 42, "foo", "bar") },
withAttrs(slog.Record{}, slog.Group("group", slog.Int("answer", 42), slog.String("foo", "bar"))),
},

"with-values-and-group": {
func() {
slog.New(ToSlogHandler(logger.WithValues("answer", 42, "foo", "bar"))).WithGroup("group").Info("")
},
// Behavior of testLogSink is not quite correct here.
withAttrs(slog.Record{}, slog.Group("group", slog.Int("answer", 42), slog.String("foo", "bar"))),
},

"with-group-and-values": {
func() {
slog.New(ToSlogHandler(logger)).WithGroup("group").With("answer", 42, "foo", "bar").Info("")
},
withAttrs(slog.Record{}, slog.Group("group", slog.Int("answer", 42), slog.String("foo", "bar"))),
},

"with-group-and-logr-values": {
func() {
slogLogger := slog.New(ToSlogHandler(logger)).WithGroup("group")
logrLogger := FromSlogHandler(slogLogger.Handler()).WithValues("answer", 42, "foo", "bar")
slogLogger = slog.New(ToSlogHandler(logrLogger))
slogLogger.Info("")
},
withAttrs(slog.Record{}, slog.Group("group", slog.Int("answer", 42), slog.String("foo", "bar"))),
},
}

for name, tc := range testcases {
t.Run(name, func(t *testing.T) {
tc.run()
verify(t, tc.expectedRecord)
reset()
})
}
}
9 changes: 9 additions & 0 deletions logr_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,13 @@ type testLogSink struct {
fnError func(err error, msg string, kv ...any)
fnWithValues func(kv ...any)
fnWithName func(name string)

withValues []any

// testSlogSink contains some additional fields if (and only if) slog is supported by Go.
// See logr_slog_test.go.
//nolint:unused // Only unused with Go < 1.21.
testSlogSink
}

var _ LogSink = &testLogSink{}
Expand Down Expand Up @@ -67,6 +74,8 @@ func (l *testLogSink) WithValues(kv ...any) LogSink {
l.fnWithValues(kv...)
}
out := *l
n := len(out.withValues)
out.withValues = append(out.withValues[:n:n], kv...)
return &out
}

Expand Down

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