refactor: Merge remaining test pairs

Merge 2 additional test pairs:
- multipleFuncArgsBothGood + multipleFuncArgsBothBad -> multipleFuncArgsBoth
- interfaceMethodWithCtxArgument + interfaceMethodWithoutCtxArgument -> interfaceMethodWithArgument

Total tests reduced from 237 to 235.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: mpyw

testdata/metatest/structure.json

@@ -1977,42 +1977,6 @@
       },
       "level": "advanced"
     },
-    "interfaceMethodWithCtxArgument": {
-      "title": "Interface method with ctx argument",
-      "targets": [
-        "errgroup",
-        "waitgroup"
-      ],
-      "variants": {
-        "good": {
-          "description": "Context is passed as argument to interface method.",
-          "functions": {
-            "errgroup": "goodInterfaceMethodWithCtxArg",
-            "waitgroup": "goodInterfaceMethodWithCtxArg"
-          }
-        },
-        "bad": null
-      },
-      "level": "evil"
-    },
-    "interfaceMethodWithoutCtxArgument": {
-      "title": "Interface method without ctx argument",
-      "targets": [
-        "errgroup",
-        "waitgroup"
-      ],
-      "variants": {
-        "bad": {
-          "description": "Interface method call without context argument.",
-          "functions": {
-            "errgroup": "badInterfaceMethodWithoutCtxArg",
-            "waitgroup": "badInterfaceMethodWithoutCtxArg"
-          }
-        },
-        "good": null
-      },
-      "level": "evil"
-    },
     "interleavedLayersCtxNoCtxCtxShadowing": {
       "title": "Interleaved layers - ctx->no ctx->ctx shadowing",
       "targets": [
@@ -2935,38 +2899,6 @@
       },
       "level": "basic"
     },
-    "multipleFuncArgsBothBad": {
-      "title": "Multiple func args - both bad",
-      "targets": [
-        "goroutinecreator"
-      ],
-      "variants": {
-        "bad": {
-          "description": "Multiple function arguments, none use context.",
-          "functions": {
-            "goroutinecreator": "badMultipleFuncs"
-          }
-        },
-        "good": null
-      },
-      "level": "creator"
-    },
-    "multipleFuncArgsBothGood": {
-      "title": "Multiple func args - both good",
-      "targets": [
-        "goroutinecreator"
-      ],
-      "variants": {
-        "good": {
-          "description": "Multiple function arguments, all use context.",
-          "functions": {
-            "goroutinecreator": "goodMultipleFuncs"
-          }
-        },
-        "bad": null
-      },
-      "level": "creator"
-    },
     "multipleFuncArgsFirstBad": {
       "title": "Multiple func args - first bad",
       "targets": [
@@ -4125,6 +4057,51 @@
           }
         }
       }
+    },
+    "multipleFuncArgsBoth": {
+      "title": "Multiple func args - both context usage",
+      "targets": [
+        "goroutinecreator"
+      ],
+      "level": "creator",
+      "variants": {
+        "good": {
+          "description": "Multiple function arguments, all use context.",
+          "functions": {
+            "goroutinecreator": "goodMultipleFuncs"
+          }
+        },
+        "bad": {
+          "description": "Multiple function arguments, none use context.",
+          "functions": {
+            "goroutinecreator": "badMultipleFuncs"
+          }
+        }
+      }
+    },
+    "interfaceMethodWithArgument": {
+      "title": "Interface method with argument",
+      "targets": [
+        "errgroup",
+        "waitgroup"
+      ],
+      "level": "evil",
+      "variants": {
+        "good": {
+          "description": "Context is passed as argument to interface method.",
+          "functions": {
+            "errgroup": "goodInterfaceMethodWithCtxArg",
+            "waitgroup": "goodInterfaceMethodWithCtxArg"
+          }
+        },
+        "bad": {
+          "description": "Interface method call without context argument.",
+          "functions": {
+            "errgroup": "badInterfaceMethodWithoutCtxArg",
+            "waitgroup": "badInterfaceMethodWithoutCtxArg"
+          }
+        }
+      }
     }
   }
 }

testdata/src/errgroup/evil.go

@@ -164,7 +164,7 @@ func (f *myFactory) CreateWorker(ctx context.Context) func() error {
 	}
 }
 
-// [GOOD]: Interface method with ctx argument
+// [GOOD]: Interface method with argument
 //
 // Context is passed as argument to interface method.
 //
@@ -181,7 +181,7 @@ type WorkerFactoryNoCtx interface {
 	CreateWorker() func() error
 }
 
-// [BAD]: Interface method without ctx argument
+// [BAD]: Interface method with argument
 //
 // Interface method call without context argument.
 //

testdata/src/goroutinecreator/creator.go

@@ -70,7 +70,7 @@ func badInlineFuncLiteral(ctx context.Context) {
 	_ = g.Wait()
 }
 
-// [BAD]: Multiple func args - both bad
+// [BAD]: Multiple func args - both context usage
 //
 // Multiple function arguments, none use context.
 func badMultipleFuncs(ctx context.Context) {
@@ -139,7 +139,7 @@ func goodInlineFuncLiteral(ctx context.Context) {
 	_ = g.Wait()
 }
 
-// [GOOD]: Multiple func args - both good
+// [GOOD]: Multiple func args - both context usage
 //
 // Multiple function arguments, all use context.
 func goodMultipleFuncs(ctx context.Context) {

testdata/src/waitgroup/evil.go

@@ -157,7 +157,7 @@ func (f *myFactory) CreateWorker(ctx context.Context) func() {
 	}
 }
 
-// [GOOD]: Interface method with ctx argument
+// [GOOD]: Interface method with argument
 //
 // Context is passed as argument to interface method.
 //
@@ -174,7 +174,7 @@ type WorkerFactoryNoCtx interface {
 	CreateWorker() func()
 }
 
-// [BAD]: Interface method without ctx argument
+// [BAD]: Interface method with argument
 //
 // Interface method call without context argument.
 //