Add appdir fixture to simplify testing

Author: vitalk

tests/conftest.py

@@ -2,9 +2,13 @@
 # -*- coding: utf-8 -*-
 import pytest
 
+from textwrap import dedent
 from flask import Flask, jsonify
 
 
+pytest_plugins = 'pytester'
+
+
 @pytest.fixture
 def app():
     app = Flask(__name__)
@@ -19,3 +23,28 @@ def ping():
         return jsonify(ping='pong')
 
     return app
+
+
+@pytest.fixture
+def appdir(testdir):
+    app_root = testdir.tmpdir
+    test_root = app_root.mkdir('tests')
+
+    def create_test_module(code, filename='test_app.py'):
+        f = test_root.join(filename)
+        f.write(dedent(code), ensure=True)
+        return f
+
+    testdir.create_test_module = create_test_module
+
+    testdir.create_test_module('''
+        import pytest
+
+        from flask import Flask
+
+        @pytest.fixture
+        def app():
+            app = Flask(__name__)
+            return app
+    ''', filename='conftest.py')
+    return testdir