I think that perhaps a bit more explanation might be helpful
I have an established pattern of capturing log messages so that i can check
them in unit tests. (The code/test first example)
I want to do that with slog (where slog emits a message and I capture that
message and compare it in the test), as partially demonstrated in the final
test section..
I've also discovered that i want to drop parts of the message (eg. the
timestamp).
The goal is to be able to trigger the SUT to emit a log message that can be
tested as both existing, and matching what is expected.
On Thursday, June 15, 2023 at 2:44:39 AM UTC+10 Tamás Gulácsi wrote:
> github.com/UNO-SOFT/zlog/v2
> NewT(t).SLog()
> returns an *slog.Logger that uses t.Log for printing.
>
> But maybe I don't understand your real problem.
>
> shan...@gmail.com a következőt írta (2023. június 14., szerda, 2:14:27
> UTC+2):
>
>> In the past when I wanted to 'capture' the log output so that I could
>> check it in a unit test I would 'hijack' os.Stdout like so
>> ```
>> var osStdout = os.Stdout
>> func MyCode (){
>> log.SetOutput(osStdout)
>> log.Print("My dog has fleas")
>> }
>> ```
>> Which could then be tested thus
>> ```
>> func TestMyCode(t *testing.T){
>> testcases := map[string]struct{
>> output string
>> }{
>> "Dog needs flea shampoo": {
>> output: "My dog has fleas",
>> },
>> }
>> for name, tc := range testcases {
>> t.Run(name, func(t *testing.T) {
>> orig := osStdout
>> flags := log.Flags()
>> log.SetFlags(0)
>> reader, writer, err := os.Pipe()
>> if err != nil {
>> panic(err)
>> }
>> osStdout = writer
>> defer func() {
>> osStdout = orig
>> log.SetFlags(flags)
>> }()
>> MyCode()
>> writer.Close()
>>
>> var buf strings.Builder
>> if _, ioerr := io.Copy(&buf, reader); ioerr != nil {
>> log.Fatalf("Copy error, cannot continue %v\n", ioerr)
>> }
>>
>> assert.Equal(t, tc.output, buf.String(), "Expected: %s Got:
>> %s", tc.output, buf.String())
>> }
>> })
>> }
>> }
>> ```
>>
>> I'm now trying to do the same with the slog package (but not having any
>> joy) - is there an established pattern that people are using, eg. is the
>> handler being
>>
>> I've been trying
>> ```
>> func TestMyCode(t *testing.T){
>> testcases := map[string]struct{
>> output string
>> }{
>> "Dog needs flea shampoo": {
>> output: "My dog has fleas",
>> },
>> }
>> for name, tc := range testcases {
>> t.Run(name, func(t *testing.T) {
>> orig := osStdout
>> reader, writer, err := os.Pipe()
>> if err != nil {
>> panic(err)
>> }
>> osStdout = writer
>> defer func() {
>> osStdout = orig
>> }()
>> slog.SetDefault(slog.New(slog.NewTextHandler(osStdout)
>> MyCode()
>> writer.Close()
>>
>> var buf strings.Builder
>> if _, ioerr := io.Copy(&buf, reader); ioerr != nil {
>> log.Fatalf("Copy error, cannot continue %v\n", ioerr)
>> }
>>
>> assert.Equal(t, tc.output, buf.String(), "Expected: %s Got:
>> %s", tc.output, buf.String())
>> }
>> })
>> }
>> }
>> ```
>>
>> Which "works" but I am not happy with it, because it's affecting all of
>> the slog instances.
>>
>> I saw previously that someone was creating their own implementation of a
>> slog.Handler? to make testing easier, and would love to see it, and will
>> that allow me to run multiple slog based tests concurrently?
>>
>
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