test: reduce and improve tests in src/compile/codemods/

src/compile/codemods/0002_pool_object_form.rs

@@ -90,17 +90,6 @@ mod tests {
         }
     }
 
-    #[test]
-    fn rewrites_scalar_pool_to_name_object() {
-        let mut fm: Mapping = serde_yaml::from_str("name: x\ndescription: y\npool: MyPool").unwrap();
-        let changed = apply_codemod(&mut fm, &ctx("0.30.0")).expect("apply");
-        assert!(changed);
-        assert_eq!(
-            fm.get(Value::String("pool".into())).cloned(),
-            Some(serde_yaml::from_str::<Value>("name: MyPool").unwrap())
-        );
-    }
-
     #[test]
     fn noops_when_pool_is_already_mapping() {
         let mut fm: Mapping =
@@ -128,21 +117,17 @@ mod tests {
 
     #[test]
     fn noops_when_pool_absent_standalone_and_version_gte() {
-        // Standalone pipelines without pool should get the new
-        // vmImage: ubuntu-22.04 default, not the legacy 1ES pool.
-        let mut fm: Mapping = serde_yaml::from_str("name: x\ndescription: y").unwrap();
-        let changed = apply_codemod(&mut fm, &ctx("0.30.0")).expect("apply");
-        assert!(!changed);
-        assert!(!fm.contains_key(Value::String("pool".into())));
-    }
-
-    #[test]
-    fn noops_when_pool_absent_explicit_standalone_and_version_gte() {
-        let mut fm: Mapping =
-            serde_yaml::from_str("name: x\ndescription: y\ntarget: standalone").unwrap();
-        let changed = apply_codemod(&mut fm, &ctx("0.30.0")).expect("apply");
-        assert!(!changed);
-        assert!(!fm.contains_key(Value::String("pool".into())));
+        // Neither implicit nor explicit `standalone` target should
+        // ever receive the legacy 1ES pool injection.
+        for yaml in &[
+            "name: x\ndescription: y",
+            "name: x\ndescription: y\ntarget: standalone",
+        ] {
+            let mut fm: Mapping = serde_yaml::from_str(yaml).unwrap();
+            let changed = apply_codemod(&mut fm, &ctx("0.30.0")).expect("apply");
+            assert!(!changed, "yaml: {}", yaml);
+            assert!(!fm.contains_key(Value::String("pool".into())), "yaml: {}", yaml);
+        }
     }
 
     #[test]

src/compile/codemods/mod.rs

@@ -181,9 +181,6 @@ mod tests {
 
     #[test]
     fn registry_ids_are_unique() {
-        // Vacuously true while CODEMODS is empty; the assertion
-        // machinery still compiles so this test guards against
-        // duplicate ids the moment a real codemod ships.
         let mut seen = std::collections::BTreeSet::new();
         for c in CODEMODS {
             assert!(
@@ -196,10 +193,9 @@ mod tests {
 
     #[test]
     fn codemod_filenames_match_registry_count() {
-        // Vacuously true while CODEMODS is empty (the directory
-        // contains only `mod.rs` and `helpers.rs`, which are
-        // skipped). Once a numeric `<NNNN>_<id>.rs` file lands, this
-        // test asserts the registry was updated to match.
+        // Each numeric `<NNNN>_<id>.rs` file must have a corresponding
+        // entry in CODEMODS; forgetting to register a new codemod
+        // in the slice is caught here.
         let dir = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
             .join("src/compile/codemods");
         let mut numeric_files: Vec<String> = Vec::new();
@@ -309,12 +305,17 @@ mod tests {
 
     #[test]
     fn non_matching_codemod_omitted_from_report() {
-        // Source has no `a` key, so the rename is a no-op and is
-        // not listed in the report.
+        // Source has no `a` key, so the rename is a no-op and must
+        // not appear in the applied list.
         let mut m: Mapping = serde_yaml::from_str("name: x\n").unwrap();
         let registry: &[&'static Codemod] = &[&TEST_CODEMOD_RENAME];
         let report = apply_codemods_with(&mut m, registry).unwrap();
         assert!(!report.changed());
+        assert!(
+            report.applied_ids().is_empty(),
+            "non-matching codemod must not appear in applied list, got: {:?}",
+            report.applied_ids()
+        );
     }
 
     #[test]