Precalculate testcase steps in setup

Author: nipunn1313

mypy/test/data.py

@@ -276,6 +276,25 @@ def setup(self) -> None:
             with open(path, 'w', encoding='utf8') as f:
                 f.write(content)
 
+        # Precalculate steps for find_steps()
+        steps: Dict[int, List[FileOperation]] = {}
+        for path, _ in self.files:
+            m = re.match(r'.*\.([0-9]+)$', path)
+            if m:
+                num = int(m.group(1))
+                assert num >= 2
+                target_path = re.sub(r'\.[0-9]+$', '', path)
+                module = module_from_path(target_path)
+                operation = UpdateFile(module, path, target_path)
+                steps.setdefault(num, []).append(operation)
+        for num, paths in self.deleted_paths.items():
+            assert num >= 2
+            for path in paths:
+                module = module_from_path(path)
+                steps.setdefault(num, []).append(DeleteFile(module, path))
+        max_step = max(steps) if steps else 2
+        self.steps = [steps.get(num, []) for num in range(2, max_step + 1)]
+
     def teardown(self) -> None:
         assert self.old_cwd is not None and self.tmpdir is not None, \
             "test was not properly set up"
@@ -312,23 +331,7 @@ def find_steps(self) -> List[List[FileOperation]]:
 
         Defaults to having two steps if there aern't any operations.
         """
-        steps: Dict[int, List[FileOperation]] = {}
-        for path, _ in self.files:
-            m = re.match(r'.*\.([0-9]+)$', path)
-            if m:
-                num = int(m.group(1))
-                assert num >= 2
-                target_path = re.sub(r'\.[0-9]+$', '', path)
-                module = module_from_path(target_path)
-                operation = UpdateFile(module, path, target_path)
-                steps.setdefault(num, []).append(operation)
-        for num, paths in self.deleted_paths.items():
-            assert num >= 2
-            for path in paths:
-                module = module_from_path(path)
-                steps.setdefault(num, []).append(DeleteFile(module, path))
-        max_step = max(steps) if steps else 2
-        return [steps.get(num, []) for num in range(2, max_step + 1)]
+        return self.steps
 
 
 def module_from_path(path: str) -> str: