[coverage-improver] Cover StubAdapter::to_artifact error branch

[TheLarkInn]

What branch was uncovered

File: crates/libaipm/src/migrate/adapters/mod.rs
Function: StubAdapter::to_artifact (test-only stub used in migrate::adapters registry ordering/object-safety tests)

The Err(Error::UnsupportedSource(...)) branch of this stub's to_artifact implementation was never exercised — existing tests only called stub.name() and stub.applies_to(...), leaving the file at 88.89% region branch coverage (8/9 hit).

What scenario the new test covers

Added stub_adapter_to_artifact_returns_unsupported_source_error, which constructs a StubAdapter, calls to_artifact with a minimal DiscoveredFeature, and asserts it returns Err(Error::UnsupportedSource(msg)) where msg contains "stub". This directly exercises the previously-uncovered error branch.

Before/after branch coverage

• adapters/mod.rs branch coverage: 88.89% → 100.00%
• Overall workspace branch coverage: 90.64% → 90.66%

Test code added

#[test]
fn stub_adapter_to_artifact_returns_unsupported_source_error() {
    // Exercises StubAdapter::to_artifact, which always errs — covers the
    // otherwise-unreachable Err branch of the stub used only for
    // ordering/object-safety tests above.
    let stub = StubAdapter;
    let feat = DiscoveredFeature {
        kind: crate::discovery::FeatureKind::Skill,
        source: crate::discovery::types::DiscoverySource::CLAUDE,
        layout: crate::discovery::Layout::Canonical,
        source_root: std::path::PathBuf::from(".claude"),
        feature_dir: None,
        path: std::path::PathBuf::from(".claude/skills/x/SKILL.md"),
    };
    let result = stub.to_artifact(&feat, &crate::fs::Real);
    assert!(matches!(result, Err(Error::UnsupportedSource(msg)) if msg.contains("stub")));
}

Verification

• cargo build --workspace ✅
• cargo test --workspace ✅ (all pass, including the new test)
• cargo fmt --check ✅
• cargo clippy --workspace -- -D warnings: pre-existing failures unrelated to this change (manual_is_variant_and lint in resolver/mod.rs and security.rs, confirmed present on main before this change too — already being tracked/fixed by PR fix(clippy): use Result::is_ok_and for Rust 1.98.0 manual_is_variant_and lint #1631)

Generated by Coverage Improver · auto · 118.7 AIC · ⌖ 4.01 AIC · ⊞ 13.1K · ◷

---

Note

This was originally intended as a pull request, but PR creation failed. The changes have been pushed to the branch coverage-improver/stub-adapter-to-artifact-error-25f55f1f1013a8f3.

Original error: ERR_API: [2026-08-20T23:37:21.337Z] create pull request in TheLarkInn/aipm failed (attempt 1)

Original error: Resource not accessible by personal access token - https://docs.github.com/rest/pulls/pulls#create-a-pull-request
Retryable: false
Suggestion: This error cannot be resolved by retrying. Please check the error details and fix the underlying issue.

To create the pull request manually:

gh pr create --title "[coverage-improver] Cover StubAdapter::to_artifact error branch" --base main --head coverage-improver/stub-adapter-to-artifact-error-25f55f1f1013a8f3 --repo TheLarkInn/aipm

Show patch preview (47 of 47 lines)

From 2746a884c7623ecd4bcd8cecd539ef4488654b0f Mon Sep 17 00:00:00 2001
X-GH-AW-Base-Commit: 6d3368da0e97be67cb075dba37b9b384df816358
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Thu, 20 Aug 2026 23:35:19 +0000
Subject: [PATCH] test(migrate): cover StubAdapter::to_artifact error branch

Add a unit test exercising the Err path of the test-only StubAdapter
used in migrate::adapters registry ordering/object-safety tests. This
branch was previously unreachable, dropping adapters/mod.rs branch
coverage to 88.89%.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 crates/libaipm/src/migrate/adapters/mod.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/crates/libaipm/src/migrate/adapters/mod.rs b/crates/libaipm/src/migrate/adapters/mod.rs
index 322631f..d8dd82c 100644
--- a/crates/libaipm/src/migrate/adapters/mod.rs
+++ b/crates/libaipm/src/migrate/adapters/mod.rs
@@ -142,4 +142,22 @@ mod tests {
         let stub: Box<dyn Adapter> = Box::new(StubAdapter);
         assert_eq!(stub.name(), "stub");
     }
+
+    #[test]
+    fn stub_adapter_to_artifact_returns_unsupported_source_error() {
+        // Exercises StubAdapter::to_artifact, which always errs — covers the
+        // otherwise-unreachable Err branch of the stub used only for
+        // ordering/object-safety tests above.
+        let stub = StubAdapter;
+        let feat = DiscoveredFeature {
+            kind: crate::discovery::FeatureKind::Skill,
+            source: crate::discovery::types::DiscoverySource::CLAUDE,
+            layout: crate::discovery::Layout::Canonical,
+            source_root: std::path::PathBuf::from(".claude"),
+            feature_dir: None,
+            path: std::path::PathBuf::from(".claude/skills/x/SKILL.md"),
+        };
+        let result = stub.to_artifact(&feat, &crate::fs::Real);
+        assert!(matches!(result, Err(Error::UnsupportedSource(msg)) if msg.contains("stub")));
+    }
 }
-- 
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