[test] Add tests for difc.IsSingularReadTool

[github-actions]

Test Coverage Improvement: IsSingularReadTool

Function Analyzed

• Package: internal/difc
• Function: IsSingularReadTool
• File: internal/difc/tool_classification.go
• Previous Coverage: 0%
• New Coverage: 100%
• Package Coverage: 99.7% → 99.9%
• Complexity: Low (single-line function with two prefix checks)

Why This Function?

IsSingularReadTool had 0% coverage with no test file at all — the clearest possible testing gap. Despite its simplicity, it plays an important semantic role in the DIFC pipeline: it distinguishes between singular read tools (e.g. get_issue, issue_read) and collection tools (e.g. list_issues, search_code). The distinction determines whether a filtered result returns an MCP error vs an empty list (see usage in internal/server/unified.go).

Tests Added

• ✅ Singular read tools: get_*, *_read, create_*, update_*, delete_*, read_* — all return true
• ✅ list_ prefix: list_issues, list_commits, list_pull_requests, list_ alone — all return false
• ✅ search_ prefix: search_code, search_issues, search_pull_requests, search_ alone — all return false
• ✅ No underscore edge cases: list, search (no _) — return true
• ✅ Similar-but-non-matching prefixes: listed_, listing_, searching_ — return true
• ✅ Names containing keywords mid-string: get_list, global_search — return true
• ✅ Case sensitivity: List_, LIST_, Search_, SEARCH_ (uppercase) — return true
• ✅ Boundary inputs: empty string, single character — return true

Coverage Report

Before: 0.0% coverage  (IsSingularReadTool)
After:  100.0% coverage (IsSingularReadTool)
Package improvement: 99.7% → 99.9%

Test Execution

All 29 sub-tests pass:

--- PASS: TestIsSingularReadTool (0.00s)
    (29 sub-tests all PASS)
ok  github.com/github/gh-aw-mcpg/internal/difc  0.005s  coverage: 99.9% of statements

---

Generated by Test Coverage Improver
Next run should target the next most complex under-tested function (e.g. LogUnrecognizedEndpointPassthrough at 75% or BuildVersionString at 89.5%)

Warning

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Generated by Test Coverage Improver · 224.6 AIC · ⊞ 7.1K · ◷

[Copilot]

Pull request overview

Adds direct unit test coverage for internal/difc.IsSingularReadTool, ensuring the DIFC package itself exercises the list_/search_ prefix heuristic used to classify collection vs. singular tool calls.

Changes:

• Add a new table-driven test suite for IsSingularReadTool covering list_/search_ prefixes and several edge cases.
• Run each case as a parallel subtest for fast execution.

Show a summary per file

File	Description
internal/difc/tool_classification_test.go	Introduces unit tests to cover IsSingularReadTool behavior across typical and edge-case tool names.

Review details

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• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low