[test] Add tests for config.stripExtensionFieldsForValidation and assignLegacyIntAlias

[github-actions]

Test Coverage Improvement

Functions Analyzed

• Package: internal/config
• Functions: stripExtensionFieldsForValidation, assignLegacyIntAlias
• File: internal/config/config_stdin.go
• Previous Coverage: 0% (no direct tests)
• Complexity: Medium — both have multiple conditional branches

Why These Functions?

Static analysis of all source files identified these two private functions as having zero direct test coverage (confirmed via codebase-wide grep for function name references in *_test.go files).

Both functions are called on every LoadFromStdin() invocation, making them part of a critical hot path. They contain multiple branches that previously relied entirely on integration-level tests to exercise.

stripExtensionFieldsForValidation (11 branches):

• Strips top-level guards field
• Strips per-server guard, auth, and tool_response_filters fields from all servers
• Preserves guard-policies (already injected into the upstream schema)
• Handles missing mcpServers gracefully
• Returns error on malformed JSON

assignLegacyIntAlias (5 branches):

• Skips when target pointer is already set (priority: new field wins)
• No-ops when alias key is absent
• Unmarshals and assigns a valid integer
• Returns an error for non-integer JSON values
• Returns an error for malformed JSON

Tests Added

• ✅ Happy path test cases for both functions
• ✅ Edge cases: empty config, missing fields, multiple servers
• ✅ Error handling: invalid JSON, malformed values, wrong types
• ✅ Branch coverage: all conditionals exercised
• ✅ Preservation verification: guard-policies kept, non-extension fields kept
• ✅ Zero and negative integer values for assignLegacyIntAlias

Test Structure

All tests follow the codebase's established table-driven pattern with testify/assert and testify/require.

---

Generated by Test Coverage Improver
Next run will target the next most complex under-tested function

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• proxy.golang.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "proxy.golang.org"

See Network Configuration for more information.

Generated by Test Coverage Improver · ● 6.4M · ◷

[Copilot]

Pull request overview

Adds direct unit coverage for private stdin configuration helpers in internal/config, focusing on extension-field stripping before schema validation and legacy integer alias assignment.

Changes:

• Adds table-driven tests for stripExtensionFieldsForValidation.
• Adds branch-focused tests for assignLegacyIntAlias.
• Covers success, no-op, and error cases for both helpers.

Show a summary per file

File	Description
internal/config/config_stdin_helpers_test.go	New unit tests for stdin config helper functions.

Copilot's findings

Tip

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

• Files reviewed: 1/1 changed files
• Comments generated: 3

[lpcox]

@copilot address review feedback

[Copilot]

@copilot address review feedback

Addressed all three review findings in the latest commit:

1. guard-policies shape (line 130): Changed fixture from array to object {"allow-only": {"repos": "public", "min-integrity": "none"}} to match the actual schema.

2. "target already set" skips unmarshalling (lines 230–234): Replaced the valid 42 alias with malformed JSON {not valid json} — the test still passes (no error returned), which proves the already-set guard fires before any parsing attempt.

3. "empty config is preserved" assertion (lines 172–173): Added wantOutputEmpty bool to the test struct and assert.Empty(t, out) in the loop, so the case now verifies the decoded output contains no keys.