fix: RoutableHandler to return handler's Enabled

[akijakya]

It seems to make sense for the RoutableHandler's Enabled method to return its handlers Enabled method instead of true.

It also fixes a bug when if a router's matcher matches the log level, the minimum log level set through &slog.HandlerOptions{} ends up being ignored (example below).

levelFilter := func(levels ...slog.Level) func(ctx context.Context, r slog.Record) bool {
    return func(ctx context.Context, r slog.Record) bool {
        return slices.Contains(levels, r.Level)
    }
}

logger := slog.New(
    slogmulti.Router().
        Add(
            slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelWarn}),
            levelFilter(slog.LevelWarn, slog.LevelError)).
        Add(
            slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}),
            levelFilter(slog.LevelDebug, slog.LevelInfo)). // before the fix, debug level logs were also sent to stdout
        Handler(),
)

[samber]

Hi @akijakya and thanks for the report.

I definitely agree with this!

BTW, I wonder why slog does not send slog.Record to Enabled(). It would be the right place to check filters, instead of Handle().

Anyway. Let's merge. -> v1.0.2

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (f892b89) 0.00% compared to head (5211a5b) 0.00%.

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Additional details and impacted files

@@          Coverage Diff          @@
##            main      #4   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
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  Files         11      11           
  Lines        248     248           
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  Misses       248     248           

Flag	Coverage Δ
unittests	0.00% <0.00%> (ø)

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Files	Coverage Δ
router.go	0.00% <0.00%> (ø)

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