From 0ea972723c41ad82b037902b65700f732e9ee9f3 Mon Sep 17 00:00:00 2001
From: Hendrik Makait <hendrik.makait@gmail.com>
Date: Mon, 22 May 2017 11:35:46 -0700
Subject: [PATCH] Auto-detect create_app() function in find_best_app() and call
 if it exists.

---
 flask/cli.py      | 13 +++++++++++++
 tests/test_cli.py | 27 +++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/flask/cli.py b/flask/cli.py
index 3d361be8..ad21d901 100644
--- a/flask/cli.py
+++ b/flask/cli.py
@@ -46,6 +46,19 @@ def find_best_app(module):
 
     if len(matches) == 1:
         return matches[0]
+
+    # Search for app factory callable.
+    app_factory = getattr(module, 'create_app', None)
+    if app_factory is not None and callable(app_factory):
+        try:
+            app = app_factory()
+            if app is not None and isinstance(app, Flask):
+                return app
+        except TypeError:
+            raise NoAppException('Auto-detected a create_app() function in '
+                                 'module "%s", but could not call it without '
+                                 'specifying arguments.' % module.__name__)
+
     raise NoAppException('Failed to find application in module "%s".  Are '
                          'you sure it contains a Flask application?  Maybe '
                          'you wrapped it in a WSGI middleware or you are '
diff --git a/tests/test_cli.py b/tests/test_cli.py
index ab875cef..53c320eb 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -51,6 +51,27 @@ def test_find_best_app(test_apps):
         myapp = Flask('appname')
     assert find_best_app(Module) == Module.myapp
 
+    class Module:
+        @staticmethod
+        def create_app():
+            return Flask('appname')
+    assert isinstance(find_best_app(Module), Flask)
+    assert find_best_app(Module).name == 'appname'
+
+    class Module:
+        myapp = Flask('appname1')
+        @staticmethod
+        def create_app():
+            return Flask('appname2')
+    assert find_best_app(Module) == Module.myapp
+
+    class Module:
+        myapp = Flask('appname1')
+        @staticmethod
+        def create_app(foo):
+            return Flask('appname2')
+    assert find_best_app(Module) == Module.myapp
+
     class Module:
         pass
     pytest.raises(NoAppException, find_best_app, Module)
@@ -60,6 +81,12 @@ def test_find_best_app(test_apps):
         myapp2 = Flask('appname2')
     pytest.raises(NoAppException, find_best_app, Module)
 
+    class Module:
+        @staticmethod
+        def create_app(foo):
+            return Flask('appname2')
+    pytest.raises(NoAppException, find_best_app, Module)
+
 
 def test_prepare_exec_for_file(test_apps):
     """Expect the correct path to be set and the correct module name to be returned.