C#: Extend TestFile instead of separate class

csharp/ql/src/utils/modeleditor/FrameworkModeEndpointsQuery.qll

@@ -7,11 +7,7 @@ private import ModelEditor
  * A class of effectively public callables from source code.
  */
 class PublicEndpointFromSource extends Endpoint {
-  PublicEndpointFromSource() {
-    this.fromSource() and
-    not this.getFile() instanceof TestFile and
-    not this.getFile() instanceof TestSupportFile
-  }
+  PublicEndpointFromSource() { this.fromSource() and not this.getFile() instanceof TestFile }
 
   override predicate isSource() { this instanceof SourceCallable }
 

csharp/ql/src/utils/modeleditor/ModelEditor.qll

@@ -110,11 +110,9 @@ string supportedType(Endpoint endpoint) {
 }
 
 string methodClassification(Call method) {
-  (method.getFile() instanceof TestFile or method.getFile() instanceof TestSupportFile) and
-  result = "test"
+  method.getFile() instanceof TestFile and result = "test"
   or
   not method.getFile() instanceof TestFile and
-  not method.getFile() instanceof TestSupportFile and
   result = "source"
 }
 
@@ -133,9 +131,8 @@ private string qualifiedCallableName(string namespace, string type, Callable c)
 }
 
 /** A file that doesn't contain tests itself, but is only used in tests. */
-class TestSupportFile extends File {
+class TestSupportFile extends TestFile {
   TestSupportFile() {
-    not this instanceof TestFile and
     this.getAbsolutePath().matches(["%/test/%", "%/tests/%"]) and
     not this.getAbsolutePath().matches("%/ql/test/%") // allows our test cases to work
   }