fix: assign set result to ctx

[chaewonkong]

• closes: Fix benchmark test to log additional fields #23

Description

• Fix LogWithZax function in the benchmark test to log added fields correctly.

Benchmark test function BenchmarkLoggingWithZax in zax_benchmark_test.go will not print added fields to context, unless context is properly provided.

in order to provide fields attached to ctx, the outcome of Set function should be reassigned to ctx.

ctx = Set(ctx, someFields) // assign result of Set to ctx.
logger.With(Get(ctx)...).Info("logging something")

How to test

Just make the benchmark function to print logs:

func BenchmarkLoggingWithZax(b *testing.B) {
	// Create a no-op logger that discards log output
	logger := zap.NewExample()
	logger = logger.WithOptions(zap.WrapCore(func(core zapcore.Core) zapcore.Core {
		enc := zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
		return zapcore.NewCore(enc, zapcore.AddSync(os.Stderr), zapcore.InfoLevel)
	}))

	for i := 1; i <= b.N; i++ {
		LogWithZax(logger)
	}
}

Result:

...
{"level":"info","ts":1742721091.128562,"msg":"logging something","field1":"value1","field2":"value2","field3":2}
{"level":"info","ts":1742721091.128564,"msg":"logging something","field1":"value1","field2":"value2","field3":2}
{"level":"info","ts":1742721091.128565,"msg":"logging something","field1":"value1","field2":"value2","field3":2}
{"level":"info","ts":1742721091.128567,"msg":"logging something","field1":"value1","field2":"value2","field3":2}
BenchmarkLoggingWithZax-8          24927             48147 ns/op            1369 B/op          7 allocs/op
PASS
ok      github.com/yuseferi/zax/v2      2.143s

[yuseferi]

Hey @chaewonkong ,

Thank you very much for your contribution!