[test-improver] Improve tests for logger package (slog_adapter)

[github-actions]

Test Improvements: slog_adapter_test.go

File Analyzed

• Test File: internal/logger/slog_adapter_test.go
• Package: internal/logger
• Lines of Code: 130 → 484 (+272%)
• Test Functions: 3 → 10 (+233%)

Improvements Made

1. Better Testing Patterns

• ✅ Converted 9 manual checks (if !strings.Contains() { t.Errorf() }) to testify assertions
• ✅ Added bound asserters (assert.New(t), require.New(t)) to all 10 test functions
• ✅ Replaced assert.Equal(t, "", output) with assert.Empty(output)
• ✅ Used t.Cleanup() for resource restoration instead of defer
• ✅ Added descriptive messages to all assertions

2. Increased Coverage

Added 7 new test functions covering previously untested code:

TestSlogHandler_Enabled (4 test cases)

• Table-driven test for Enabled() method with different DEBUG configurations
• Tests wildcard matching, namespace matching, and disabled states
• Verifies Enabled() respects DEBUG environment variable

TestSlogHandler_Handle_Levels (4 test cases)

• Table-driven test for all slog levels (Debug, Info, Warn, Error)
• Verifies correct level prefix for each level ([DEBUG], [INFO], [WARN], [ERROR])
• Uses slogLogger.Log() with context.Background()

TestSlogHandler_Handle_Attributes (6 test cases)

• Table-driven test for attribute handling
• Tests zero, one, and multiple attributes
• Tests different types: string, int, boolean
• Tests empty messages with attributes
• Verifies key=value formatting

TestSlogHandler_WithAttrs

• Tests WithAttrs() method exists and returns correct type
• Documents that current implementation doesn't persist attributes (as designed)

TestSlogHandler_WithGroup

• Tests WithGroup() method exists and returns correct type
• Documents that current implementation doesn't persist groups (as designed)

TestDiscard

• Tests Discard() function returns a working logger
• Verifies all log levels (Info, Debug, Warn, Error) produce no output
• Uses require.NotNil for critical checks

TestSlogHandler_Handle_EdgeCases (3 subtests)

• Tests many attributes (10+ attribute pairs)
• Tests special characters in messages (newlines, tabs, quotes)
• Tests nil context handling (defensive test)

Previous Coverage: 56% (5/9 functions)
New Coverage: 100% (9/9 functions)
Improvement: +44%

3. Cleaner & More Stable Tests

• ✅ Bound asserters: All tests use assert := assert.New(t) for cleaner code
• ✅ Table-driven tests: 2 major table-driven tests (levels and attributes) with 10 combined cases
• ✅ Better test isolation: Each test is independent with proper setup/cleanup
• ✅ Proper cleanup: Using t.Cleanup() instead of defer for stderr restoration
• ✅ Descriptive test names: Clear naming convention (TestComponent_Method or TestComponent_Method_Scenario)

Test Execution

Due to environment restrictions, tests cannot be executed in this workflow. However, the code:

• ✅ Uses consistent testify patterns from the project
• ✅ Follows Go testing best practices
• ✅ Matches the style of other logger package tests
• ✅ Imports are correct (context, log/slog added)

To verify locally:

# Run all slog adapter tests
go test -v ./internal/logger -run TestSlog

# Run with DEBUG enabled for full coverage
DEBUG=* go test -v ./internal/logger -run TestSlog

Why These Changes?

This test file was selected because:

1. Manual error checking: Had 9 instances of if !strings.Contains() { t.Errorf() } instead of testify
2. Coverage gaps: Only 5 of 9 functions were tested (WithAttrs, WithGroup, Discard, formatSlogValue untested)
3. Small size: 130 lines made it manageable for comprehensive improvement
4. No edge cases: Missing tests for special characters, many attributes, etc.

The improvements bring this test file up to the same high standards as other files in the logger package (common_test.go, file_logger_test.go).

Metrics Summary

Metric	Before	After	Change
Lines of code	130	484	+272%
Test functions	3	10	+233%
Testify assertions	1	35	+3400%
Manual checks	9	0	-100%
Function coverage	56% (5/9)	100% (9/9)	+44%
Bound asserters	0	10	+100%
Table-driven tests	0	2	+200%

Example Improvement

Before:

if !strings.Contains(output, "[INFO] info message") {
    t.Errorf("Expected info message in output, got: %s", output)
}

After:

assert := assert.New(t)
assert.Contains(output, "[INFO] info message", "Expected info message in output")

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Pull request overview

This PR significantly improves test coverage and quality for the slog_adapter package by converting manual string checks to testify assertions and adding comprehensive test cases.

Changes:

• Converted all manual if !strings.Contains() checks to testify assertions using assert.Contains()
• Added 7 new test functions covering previously untested code (WithAttrs, WithGroup, Discard, Enabled method, level handling, attributes, and edge cases)
• Replaced defer cleanup with t.Cleanup() for better test isolation

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