improve slogtest

[imjasonh]

Without the slogtest change, with the newly added test:

go test ./slogtest/ -v                
=== RUN   TestSlogTest
    slogtest.go:20: time=2024-02-12T16:50:56.437-05:00 level=INFO msg="hello world" foo=bar
        
--- PASS: TestSlogTest (0.00s)
PASS
ok      github.com/chainguard-dev/clog/slogtest 0.116s

With this change:

go test ./slogtest -v
=== RUN   TestSlogTest
    slogtest.go:31: level=INFO source=/Users/jason/git/clog/slogtest/slogtest_test.go:13 msg="hello world" foo=bar
    slogtest.go:31: level=INFO source=/Users/jason/git/clog/slogtest/slogtest_test.go:14 msg="me again" bar=baz
    slogtest.go:31: level=INFO source=/Users/jason/git/clog/slogtest/slogtest_test.go:15 msg="okay last one" baz=true

[imjasonh]

Also removing trailing newlines so logs go from this:

go test ./slogtest/ -v 
=== RUN   TestSlogTest
    slogtest.go:21: time=2024-02-12T17:04:57.896-05:00 level=INFO msg="hello world" foo=bar
        
    slogtest.go:21: time=2024-02-12T17:04:57.896-05:00 level=INFO msg="me again" bar=baz
        
    slogtest.go:21: time=2024-02-12T17:04:57.896-05:00 level=INFO msg="okay last one" baz=true
        
--- PASS: TestSlogTest (0.00s)
PASS

to this

go test ./slogtest/ -v 
=== RUN   TestSlogTest
    slogtest.go:21: time=2024-02-12T17:03:46.996-05:00 level=INFO msg="hello world" foo=bar
    slogtest.go:21: time=2024-02-12T17:03:46.996-05:00 level=INFO msg="me again" bar=baz
    slogtest.go:21: time=2024-02-12T17:03:46.996-05:00 level=INFO msg="okay last one" baz=true
--- PASS: TestSlogTest (0.00s)
PASS

[wlynch]

Drive-by observation - This is coming from the testing package, not slog (https://cs.opensource.google/go/go/+/refs/tags/go1.22.0:src/testing/testing.go;l=1010).

Setting AddSource: true will include the correct path.

=== RUN   TestSlogTest
    slogtest.go:20: time=2024-02-12T17:12:42.519-05:00 level=INFO source=/Users/wlynch/go/src/github.com/chainguard-dev/clog/slogtest/slogtest_test.go:12 msg="hello world" foo=bar
        
--- PASS: TestSlogTest (0.00s)
PASS
ok      github.com/chainguard-dev/clog/slogtest 0.112s

[imjasonh]

I've updated this PR to not use t.Helper, and instead just improve the experience of slogtest in general.

This deprecates slogtest.TestContextWithLogger(t) in favor of slogtest.Context(t), and adds go docs.

[wlynch]

keep this? IIRC this lets debug logs surface in test output (which follows the regular go test pattern where they only show if the test fails).