[test-improver] Improve tests for dockerutil package

[github-actions]

Test Improvements: internal/dockerutil/env_test.go

File Analyzed

• Test File: internal/dockerutil/env_test.go
• Package: internal/dockerutil
• Lines of Code: 91 → 107

Improvements Made

1. Better Testing Patterns (Testify Assertions)

• ✅ Added testify/assert and testify/require imports
• ✅ Replaced manual length-check + element-by-element loop with single assert.Equal(t, tt.expected, result) — cleaner and produces a better diff on failure
• ✅ Used require.NoError(t, os.Setenv(k, v)) to surface Setenv failures instead of silently ignoring them

2. Improved Test Case Names

• ✅ Renamed "undefined env variable" → "undefined env variable leaves arg unchanged" (more descriptive of the expected behaviour)
• ✅ Renamed "empty env variable value" → "empty env variable value expands to key=" (documents the KEY= format)

3. Increased Coverage — New Edge Cases

• ✅ nil args: passes nil as the args slice; ExpandEnvArgs should return an empty (non-nil) slice
• ✅ empty args: passes []string{}; same expectation
• ✅ -e followed by empty string arg: -e "" — the empty-string next-arg must not trigger expansion (guarded by len(nextArg) > 0)
• ✅ env value containing equals signs: value "a=b=c" must survive intact as KEY_WITH_EQUALS=a=b=c, confirming the implementation only checks the key for =, not the value

4. Removed Redundant Comments

• ✅ Removed // Set up environment variables for test and // Clean up after test — the code is self-explanatory with t.Cleanup

Why This File?

env_test.go was the only test file in the project that still used a manual two-step assertion pattern (if len != len { Fatalf } + for range { Errorf }) instead of the project-wide testify convention. The file is small and self-contained, making it a safe, low-risk improvement with clear before/after value.

---

Generated by Test Improver Workflow
Focuses on better patterns, increased coverage, and more stable tests

AI generated by Test Improver

[Copilot]

Pull request overview

This PR improves the test file for the dockerutil package by adopting project-wide testing conventions and adding edge case coverage. The changes migrate from manual two-step assertion patterns to the testify assertion library that is consistently used throughout the codebase, improving test maintainability and failure output clarity.

Changes:

• Adopted testify/assert and testify/require for cleaner assertions with better diff output on failure
• Improved test case names to be more descriptive of expected behavior
• Added four new edge case tests: nil args, empty args, empty string after -e flag, and env values containing equals signs
• Removed redundant comments that didn't add value beyond self-explanatory code

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.