Introduce class TestFile and use it.

Author: Max Schaefer

ql/src/Security/CWE-295/DisabledCertificateCheck.ql

@@ -115,5 +115,5 @@ where
     becomesPartOf*(base, init)
   ) and
   // exclude results in test code
-  exists(File fl | fl = w.getFile() | not fl = any(TestCase tc).getFile())
+  exists(File fl | fl = w.getFile() | not fl instanceof TestFile)
 select w, "InsecureSkipVerify should not be used in production code."

ql/src/filters/ClassifyFiles.ql

@@ -21,7 +21,7 @@ string generatorCommentRegex() {
 
 predicate classify(File f, string category) {
   // tests
-  f = any(TestCase tc).getFile() and
+  f instanceof TestFile and
   category = "test"
   or
   // vendored code

ql/src/semmle/go/frameworks/Testing.qll

@@ -40,3 +40,31 @@ module TestCase {
     }
   }
 }
+
+/**
+ * A file that contains test cases or is otherwise used for testing.
+ *
+ * Extend this class to refine existing models of testing frameworks. If you want to model new
+ * frameworks, extend `TestFile::Range` instead.
+ */
+class TestFile extends File {
+  TestFile::Range self;
+
+  TestFile() { this = self }
+}
+
+/** Provides classes for working with test files. */
+module TestFile {
+  /**
+   * A file that contains test cases or is otherwise used for testing.
+   *
+   * Extend this class to model new testing frameworks. If you want to refine existing models,
+   * extend `TestFile` instead.
+   */
+  abstract class Range extends File { }
+
+  /** A file containing at least one test case. */
+  private class FileContainingTestCases extends Range {
+    FileContainingTestCases() { this = any(TestCase tc).getFile() }
+  }
+}