From c96b89fdee098e13633686a1cff6d8f40d16a70a Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Tue, 19 May 2020 19:08:56 -0500
Subject: [PATCH 1/6] Improve module loading

---
 src/functions_framework/__init__.py           | 20 ++++++++++++++++---
 .../test_functions/module_is_correct/main.py  |  5 ++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/functions_framework/__init__.py b/src/functions_framework/__init__.py
index ce0e2fbf..641c715b 100644
--- a/src/functions_framework/__init__.py
+++ b/src/functions_framework/__init__.py
@@ -140,10 +140,24 @@ def create_app(target=None, source=None, signature_type=None):
     # Set the environment variable if it wasn't already
     os.environ["FUNCTION_SIGNATURE_TYPE"] = signature_type
 
-    # Load the source file
-    spec = importlib.util.spec_from_file_location("__main__", source)
+    # Load the source file:
+    # 1. Extract the module name from the source path
+    realpath = os.path.realpath(source)
+    directory, filename = os.path.split(realpath)
+    name, extension = os.path.splitext(filename)
+
+    # 2. Create a new module
+    spec = importlib.util.spec_from_file_location(name, realpath)
     source_module = importlib.util.module_from_spec(spec)
-    sys.path.append(os.path.dirname(os.path.realpath(source)))
+
+    # 3. Add the directory of the source to sys.path to allow the function to
+    # load modules relative to its location
+    sys.path.append(directory)
+
+    # 4. Add the module to sys.modules
+    sys.modules[name] = source_module
+
+    # 5. Execute the module
     spec.loader.exec_module(source_module)
 
     app = flask.Flask(target, template_folder=template_folder)
diff --git a/tests/test_functions/module_is_correct/main.py b/tests/test_functions/module_is_correct/main.py
index ed7a30cf..06d2f971 100644
--- a/tests/test_functions/module_is_correct/main.py
+++ b/tests/test_functions/module_is_correct/main.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os.path
 import typing
 
 
@@ -21,7 +22,9 @@ class TestClass:
 
 def function(request):
     # Ensure that the module for any object in this file is set correctly
-    assert TestClass.__mro__[0].__module__ == "__main__"
+    _, filename = os.path.split(__file__)
+    name, _ = os.path.splitext(filename)
+    assert TestClass.__mro__[0].__module__ == name
 
     # Ensure that calling `get_type_hints` on an object in this file succeeds
     assert typing.get_type_hints(TestClass) == {}

From 7e254c9825db073ef6ce03c310deff43644f7316 Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Wed, 20 May 2020 18:27:25 -0500
Subject: [PATCH 2/6] Remove --dry-run

---
 CHANGELOG.md                    |  2 ++
 src/functions_framework/_cli.py | 10 ++--------
 tests/test_cli.py               | 12 ------------
 3 files changed, 4 insertions(+), 20 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 583e6655..bf8c7636 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+- Removed `--dry-run` flag
 
 ## [1.4.3] - 2020-05-14
 ### Fixed
diff --git a/src/functions_framework/_cli.py b/src/functions_framework/_cli.py
index 4fe6e427..6f645f32 100644
--- a/src/functions_framework/_cli.py
+++ b/src/functions_framework/_cli.py
@@ -32,12 +32,6 @@
 @click.option("--host", envvar="HOST", type=click.STRING, default="0.0.0.0")
 @click.option("--port", envvar="PORT", type=click.INT, default=8080)
 @click.option("--debug", envvar="DEBUG", is_flag=True)
-@click.option("--dry-run", envvar="DRY_RUN", is_flag=True)
-def _cli(target, source, signature_type, host, port, debug, dry_run):
+def _cli(target, source, signature_type, host, port, debug):
     app = create_app(target, source, signature_type)
-    if dry_run:
-        click.echo("Function: {}".format(target))
-        click.echo("URL: http://{}:{}/".format(host, port))
-        click.echo("Dry run successful, shutting down.")
-    else:
-        create_server(app, debug).run(host, port)
+    create_server(app, debug).run(host, port)
diff --git a/tests/test_cli.py b/tests/test_cli.py
index aa4a901e..7613b649 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -69,18 +69,6 @@ def test_cli_no_arguments():
             [pretend.call("foo", None, "event")],
             [pretend.call("0.0.0.0", 8080)],
         ),
-        (
-            ["--target", "foo", "--dry-run"],
-            {},
-            [pretend.call("foo", None, "http")],
-            [],
-        ),
-        (
-            [],
-            {"FUNCTION_TARGET": "foo", "DRY_RUN": "True"},
-            [pretend.call("foo", None, "http")],
-            [],
-        ),
         (
             ["--target", "foo", "--host", "127.0.0.1"],
             {},

From 799e1b63a5e248b9f9ca05b24c283e7403c33afd Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Wed, 20 May 2020 18:29:13 -0500
Subject: [PATCH 3/6] Install and initialize Cloud Debugger

---
 CHANGELOG.md                        |  3 +++
 setup.py                            |  1 +
 src/functions_framework/__init__.py |  8 +++++++
 tests/test_debugger.py              | 33 +++++++++++++++++++++++++++++
 4 files changed, 45 insertions(+)
 create mode 100644 tests/test_debugger.py

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bf8c7636..c3010548 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Enable the Google Cloud debugger
+
 ### Changed
 - Removed `--dry-run` flag
 
diff --git a/setup.py b/setup.py
index 2a16fe7f..17bf312a 100644
--- a/setup.py
+++ b/setup.py
@@ -52,6 +52,7 @@
         "click>=7.0,<8.0",
         "watchdog>=0.10.0",
         "gunicorn>=19.2.0,<21.0; platform_system!='Windows'",
+        "google-python-cloud-debugger>=1.0<3.0; platform_system=='Linux'",
     ],
     extras_require={"test": ["pytest", "tox"]},
     entry_points={
diff --git a/src/functions_framework/__init__.py b/src/functions_framework/__init__.py
index 641c715b..259c5fbc 100644
--- a/src/functions_framework/__init__.py
+++ b/src/functions_framework/__init__.py
@@ -140,6 +140,14 @@ def create_app(target=None, source=None, signature_type=None):
     # Set the environment variable if it wasn't already
     os.environ["FUNCTION_SIGNATURE_TYPE"] = signature_type
 
+    # Initialize the debugger if possible
+    try:
+        import googleclouddebugger
+
+        googleclouddebugger.enable(module="[MODULE]", version="[VERSION]")
+    except ImportError:
+        pass
+
     # Load the source file:
     # 1. Extract the module name from the source path
     realpath = os.path.realpath(source)
diff --git a/tests/test_debugger.py b/tests/test_debugger.py
new file mode 100644
index 00000000..d931cf81
--- /dev/null
+++ b/tests/test_debugger.py
@@ -0,0 +1,33 @@
+import pathlib
+import sys
+
+import pretend
+
+from functions_framework import create_app
+
+TEST_FUNCTIONS_DIR = pathlib.Path.cwd() / "tests" / "test_functions"
+
+
+def test_debugger_missing(monkeypatch):
+    monkeypatch.setitem(sys.modules, "googleclouddebugger", None)
+
+    source = TEST_FUNCTIONS_DIR / "http_trigger" / "main.py"
+    target = "function"
+
+    create_app(target, source)
+
+
+def test_debugger_present(monkeypatch):
+    googleclouddebugger = pretend.stub(
+        enable=pretend.call_recorder(lambda *a, **kw: None)
+    )
+    monkeypatch.setitem(sys.modules, "googleclouddebugger", googleclouddebugger)
+
+    source = TEST_FUNCTIONS_DIR / "http_trigger" / "main.py"
+    target = "function"
+
+    create_app(target, source)
+
+    assert googleclouddebugger.enable.calls == [
+        pretend.call(module="[MODULE]", version="[VERSION]"),
+    ]

From 622655b252660d9d8ea9dc2f6d7c5b972b8b2e11 Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Wed, 20 May 2020 18:29:22 -0500
Subject: [PATCH 4/6] Lazy-load the WSGI app

The WSGI app must be created as late as possible for the debugger to
correctly capture breakpoints
---
 src/functions_framework/__init__.py       |  1 -
 src/functions_framework/_cli.py           |  6 ++---
 src/functions_framework/_http/__init__.py | 12 ++++-----
 src/functions_framework/_http/flask.py    |  4 +--
 src/functions_framework/_http/gunicorn.py | 10 +++++---
 tests/test_cli.py                         | 30 +++++++++++------------
 tests/test_http.py                        | 24 ++++++++++--------
 7 files changed, 46 insertions(+), 41 deletions(-)

diff --git a/src/functions_framework/__init__.py b/src/functions_framework/__init__.py
index 259c5fbc..b5d6f796 100644
--- a/src/functions_framework/__init__.py
+++ b/src/functions_framework/__init__.py
@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import functools
 import importlib.util
 import os.path
 import pathlib
diff --git a/src/functions_framework/_cli.py b/src/functions_framework/_cli.py
index 6f645f32..de15d098 100644
--- a/src/functions_framework/_cli.py
+++ b/src/functions_framework/_cli.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import os
+from functools import partial
 
 import click
 
@@ -33,5 +33,5 @@
 @click.option("--port", envvar="PORT", type=click.INT, default=8080)
 @click.option("--debug", envvar="DEBUG", is_flag=True)
 def _cli(target, source, signature_type, host, port, debug):
-    app = create_app(target, source, signature_type)
-    create_server(app, debug).run(host, port)
+    load_app = partial(create_app, target, source, signature_type)
+    create_server(load_app, debug).run(host, port)
diff --git a/src/functions_framework/_http/__init__.py b/src/functions_framework/_http/__init__.py
index ca9b0f5c..d1a380b0 100644
--- a/src/functions_framework/_http/__init__.py
+++ b/src/functions_framework/_http/__init__.py
@@ -16,8 +16,8 @@
 
 
 class HTTPServer:
-    def __init__(self, app, debug, **options):
-        self.app = app
+    def __init__(self, load_app, debug, **options):
+        self.load_app = load_app
         self.debug = debug
         self.options = options
 
@@ -28,15 +28,15 @@ def __init__(self, app, debug, **options):
                 from functions_framework._http.gunicorn import GunicornApplication
 
                 self.server_class = GunicornApplication
-            except ImportError as e:
+            except ImportError:
                 self.server_class = FlaskApplication
 
     def run(self, host, port):
         http_server = self.server_class(
-            self.app, host, port, self.debug, **self.options
+            self.load_app, host, port, self.debug, **self.options
         )
         http_server.run()
 
 
-def create_server(wsgi_app, debug, **options):
-    return HTTPServer(wsgi_app, debug, **options)
+def create_server(load_app, debug, **options):
+    return HTTPServer(load_app, debug, **options)
diff --git a/src/functions_framework/_http/flask.py b/src/functions_framework/_http/flask.py
index b2edf563..f0414a54 100644
--- a/src/functions_framework/_http/flask.py
+++ b/src/functions_framework/_http/flask.py
@@ -14,8 +14,8 @@
 
 
 class FlaskApplication:
-    def __init__(self, app, host, port, debug, **options):
-        self.app = app
+    def __init__(self, load_app, host, port, debug, **options):
+        self.app = load_app()
         self.host = host
         self.port = port
         self.debug = debug
diff --git a/src/functions_framework/_http/gunicorn.py b/src/functions_framework/_http/gunicorn.py
index 163b5317..67c217b5 100644
--- a/src/functions_framework/_http/gunicorn.py
+++ b/src/functions_framework/_http/gunicorn.py
@@ -15,8 +15,8 @@
 import gunicorn.app.base
 
 
-class GunicornApplication(gunicorn.app.base.BaseApplication):
-    def __init__(self, app, host, port, debug, **options):
+class GunicornApplication(gunicorn.app.base.Application):
+    def __init__(self, load_app, host, port, debug, **options):
         self.options = {
             "bind": "%s:%s" % (host, port),
             "workers": 1,
@@ -24,7 +24,7 @@ def __init__(self, app, host, port, debug, **options):
             "timeout": 0,
         }
         self.options.update(options)
-        self.app = app
+        self.load_app = load_app
         super().__init__()
 
     def load_config(self):
@@ -32,4 +32,6 @@ def load_config(self):
             self.cfg.set(key, value)
 
     def load(self):
-        return self.app
+        # The WSGI app MUST be initalized here in order for the debugger to
+        # correctly trigger breakpoints
+        return self.load_app()
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 7613b649..ab891a2b 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -19,6 +19,7 @@
 
 import functions_framework
 
+from functions_framework import create_app
 from functions_framework._cli import _cli
 
 
@@ -31,69 +32,68 @@ def test_cli_no_arguments():
 
 
 @pytest.mark.parametrize(
-    "args, env, create_app_calls, run_calls",
+    "args, env, partial_calls, run_calls",
     [
         (
             ["--target", "foo"],
             {},
-            [pretend.call("foo", None, "http")],
+            [pretend.call(create_app, "foo", None, "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             [],
             {"FUNCTION_TARGET": "foo"},
-            [pretend.call("foo", None, "http")],
+            [pretend.call(create_app, "foo", None, "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             ["--target", "foo", "--source", "/path/to/source.py"],
             {},
-            [pretend.call("foo", "/path/to/source.py", "http")],
+            [pretend.call(create_app, "foo", "/path/to/source.py", "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             [],
             {"FUNCTION_TARGET": "foo", "FUNCTION_SOURCE": "/path/to/source.py"},
-            [pretend.call("foo", "/path/to/source.py", "http")],
+            [pretend.call(create_app, "foo", "/path/to/source.py", "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             ["--target", "foo", "--signature-type", "event"],
             {},
-            [pretend.call("foo", None, "event")],
+            [pretend.call(create_app, "foo", None, "event")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             [],
             {"FUNCTION_TARGET": "foo", "FUNCTION_SIGNATURE_TYPE": "event"},
-            [pretend.call("foo", None, "event")],
+            [pretend.call(create_app, "foo", None, "event")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             ["--target", "foo", "--host", "127.0.0.1"],
             {},
-            [pretend.call("foo", None, "http")],
+            [pretend.call(create_app, "foo", None, "http")],
             [pretend.call("127.0.0.1", 8080)],
         ),
         (
             ["--target", "foo", "--debug"],
             {},
-            [pretend.call("foo", None, "http")],
+            [pretend.call(create_app, "foo", None, "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
         (
             [],
             {"FUNCTION_TARGET": "foo", "DEBUG": "True"},
-            [pretend.call("foo", None, "http")],
+            [pretend.call(create_app, "foo", None, "http")],
             [pretend.call("0.0.0.0", 8080)],
         ),
     ],
 )
-def test_cli(monkeypatch, args, env, create_app_calls, run_calls):
+def test_cli(monkeypatch, args, env, partial_calls, run_calls):
     wsgi_server = pretend.stub(run=pretend.call_recorder(lambda *a, **kw: None))
-    wsgi_app = pretend.stub(run=pretend.call_recorder(lambda *a, **kw: None))
-    create_app = pretend.call_recorder(lambda *a, **kw: wsgi_app)
-    monkeypatch.setattr(functions_framework._cli, "create_app", create_app)
+    partial = pretend.call_recorder(lambda *a, **kw: pretend.stub())
+    monkeypatch.setattr(functions_framework._cli, "partial", partial)
     create_server = pretend.call_recorder(lambda *a, **kw: wsgi_server)
     monkeypatch.setattr(functions_framework._cli, "create_server", create_server)
 
@@ -101,5 +101,5 @@ def test_cli(monkeypatch, args, env, create_app_calls, run_calls):
     result = runner.invoke(_cli, args)
 
     assert result.exit_code == 0
-    assert create_app.calls == create_app_calls
+    assert partial.calls == partial_calls
     assert wsgi_server.run.calls == run_calls
diff --git a/tests/test_http.py b/tests/test_http.py
index e9929d94..e1236ee3 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -26,12 +26,12 @@ def test_create_server(monkeypatch, debug):
     server_stub = pretend.stub()
     httpserver = pretend.call_recorder(lambda *a, **kw: server_stub)
     monkeypatch.setattr(functions_framework._http, "HTTPServer", httpserver)
-    wsgi_app = pretend.stub()
+    load_app = pretend.stub()
     options = {"a": pretend.stub(), "b": pretend.stub()}
 
-    functions_framework._http.create_server(wsgi_app, debug, **options)
+    functions_framework._http.create_server(load_app, debug, **options)
 
-    assert httpserver.calls == [pretend.call(wsgi_app, debug, **options)]
+    assert httpserver.calls == [pretend.call(load_app, debug, **options)]
 
 
 @pytest.mark.parametrize(
@@ -44,7 +44,7 @@ def test_create_server(monkeypatch, debug):
     ],
 )
 def test_httpserver(monkeypatch, debug, gunicorn_missing, expected):
-    app = pretend.stub()
+    load_app = pretend.stub()
     http_server = pretend.stub(run=pretend.call_recorder(lambda: None))
     server_classes = {
         "flask": pretend.call_recorder(lambda *a, **kw: http_server),
@@ -64,9 +64,9 @@ def test_httpserver(monkeypatch, debug, gunicorn_missing, expected):
             gunicorn, "GunicornApplication", server_classes["gunicorn"],
         )
 
-    wrapper = functions_framework._http.HTTPServer(app, debug, **options)
+    wrapper = functions_framework._http.HTTPServer(load_app, debug, **options)
 
-    assert wrapper.app == app
+    assert wrapper.load_app == load_app
     assert wrapper.server_class == server_classes[expected]
     assert wrapper.options == options
 
@@ -76,7 +76,7 @@ def test_httpserver(monkeypatch, debug, gunicorn_missing, expected):
     wrapper.run(host, port)
 
     assert wrapper.server_class.calls == [
-        pretend.call(app, host, port, debug, **options)
+        pretend.call(load_app, host, port, debug, **options)
     ]
     assert http_server.run.calls == [pretend.call()]
 
@@ -85,6 +85,7 @@ def test_httpserver(monkeypatch, debug, gunicorn_missing, expected):
 @pytest.mark.parametrize("debug", [True, False])
 def test_gunicorn_application(debug):
     app = pretend.stub()
+    load_app = pretend.call_recorder(lambda: app)
     host = "1.2.3.4"
     port = "1234"
     options = {}
@@ -92,10 +93,10 @@ def test_gunicorn_application(debug):
     import functions_framework._http.gunicorn
 
     gunicorn_app = functions_framework._http.gunicorn.GunicornApplication(
-        app, host, port, debug, **options
+        load_app, host, port, debug, **options
     )
 
-    assert gunicorn_app.app == app
+    assert gunicorn_app.load_app == load_app
     assert gunicorn_app.options == {
         "bind": "%s:%s" % (host, port),
         "workers": 1,
@@ -108,17 +109,19 @@ def test_gunicorn_application(debug):
     assert gunicorn_app.cfg.threads == 8
     assert gunicorn_app.cfg.timeout == 0
     assert gunicorn_app.load() == app
+    assert gunicorn_app.load_app.calls == [pretend.call()]
 
 
 @pytest.mark.parametrize("debug", [True, False])
 def test_flask_application(debug):
     app = pretend.stub(run=pretend.call_recorder(lambda *a, **kw: None))
+    load_app = pretend.call_recorder(lambda: app)
     host = pretend.stub()
     port = pretend.stub()
     options = {"a": pretend.stub(), "b": pretend.stub()}
 
     flask_app = functions_framework._http.flask.FlaskApplication(
-        app, host, port, debug, **options
+        load_app, host, port, debug, **options
     )
 
     assert flask_app.app == app
@@ -126,6 +129,7 @@ def test_flask_application(debug):
     assert flask_app.port == port
     assert flask_app.debug == debug
     assert flask_app.options == options
+    assert load_app.calls == [pretend.call()]
 
     flask_app.run()
 

From b3c3241b4b69692d8861f924410d36ec1f61fa12 Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Wed, 20 May 2020 22:40:44 -0500
Subject: [PATCH 5/6] Handle DefaultCredentialsError

---
 src/functions_framework/__init__.py |  3 +++
 tests/test_debugger.py              | 26 +++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/functions_framework/__init__.py b/src/functions_framework/__init__.py
index b5d6f796..a5fcd84a 100644
--- a/src/functions_framework/__init__.py
+++ b/src/functions_framework/__init__.py
@@ -142,10 +142,13 @@ def create_app(target=None, source=None, signature_type=None):
     # Initialize the debugger if possible
     try:
         import googleclouddebugger
+        from google.auth.exceptions import DefaultCredentialsError
 
         googleclouddebugger.enable(module="[MODULE]", version="[VERSION]")
     except ImportError:
         pass
+    except DefaultCredentialsError:
+        pass
 
     # Load the source file:
     # 1. Extract the module name from the source path
diff --git a/tests/test_debugger.py b/tests/test_debugger.py
index d931cf81..5cfcbcac 100644
--- a/tests/test_debugger.py
+++ b/tests/test_debugger.py
@@ -17,11 +17,35 @@ def test_debugger_missing(monkeypatch):
     create_app(target, source)
 
 
-def test_debugger_present(monkeypatch):
+def test_debugger_present_no_default_credentials(monkeypatch):
+    class DefaultCredentialsError(Exception):
+        pass
+
+    googleauthexceptions = pretend.stub(DefaultCredentialsError=DefaultCredentialsError)
+    monkeypatch.setitem(sys.modules, "google.auth.exceptions", googleauthexceptions)
+
+    googleclouddebugger = pretend.stub(
+        enable=pretend.call_recorder(pretend.raiser(DefaultCredentialsError))
+    )
+    monkeypatch.setitem(sys.modules, "googleclouddebugger", googleclouddebugger)
+
+    source = TEST_FUNCTIONS_DIR / "http_trigger" / "main.py"
+    target = "function"
+
+    create_app(target, source)
+
+    assert googleclouddebugger.enable.calls == [
+        pretend.call(module="[MODULE]", version="[VERSION]"),
+    ]
+
+
+def test_debugger_present_with_default_credentials(monkeypatch):
     googleclouddebugger = pretend.stub(
         enable=pretend.call_recorder(lambda *a, **kw: None)
     )
     monkeypatch.setitem(sys.modules, "googleclouddebugger", googleclouddebugger)
+    googleauthexceptions = pretend.stub(DefaultCredentialsError=pretend.stub())
+    monkeypatch.setitem(sys.modules, "google.auth.exceptions", googleauthexceptions)
 
     source = TEST_FUNCTIONS_DIR / "http_trigger" / "main.py"
     target = "function"

From 9c20b45c32fd1fd2cee2107e7e0b63dee78b4108 Mon Sep 17 00:00:00 2001
From: Dustin Ingram <di@users.noreply.github.com>
Date: Wed, 20 May 2020 22:57:23 -0500
Subject: [PATCH 6/6] Handle RuntimeError

---
 src/functions_framework/__init__.py |  2 ++
 tests/test_debugger.py              | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/functions_framework/__init__.py b/src/functions_framework/__init__.py
index a5fcd84a..24602632 100644
--- a/src/functions_framework/__init__.py
+++ b/src/functions_framework/__init__.py
@@ -149,6 +149,8 @@ def create_app(target=None, source=None, signature_type=None):
         pass
     except DefaultCredentialsError:
         pass
+    except RuntimeError:
+        pass
 
     # Load the source file:
     # 1. Extract the module name from the source path
diff --git a/tests/test_debugger.py b/tests/test_debugger.py
index 5cfcbcac..6391e31d 100644
--- a/tests/test_debugger.py
+++ b/tests/test_debugger.py
@@ -39,11 +39,34 @@ class DefaultCredentialsError(Exception):
     ]
 
 
+def test_debugger_present_and_already_attached(monkeypatch):
+    class DefaultCredentialsError(Exception):
+        pass
+
+    googleauthexceptions = pretend.stub(DefaultCredentialsError=DefaultCredentialsError)
+    monkeypatch.setitem(sys.modules, "google.auth.exceptions", googleauthexceptions)
+
+    googleclouddebugger = pretend.stub(
+        enable=pretend.call_recorder(pretend.raiser(RuntimeError))
+    )
+    monkeypatch.setitem(sys.modules, "googleclouddebugger", googleclouddebugger)
+
+    source = TEST_FUNCTIONS_DIR / "http_trigger" / "main.py"
+    target = "function"
+
+    create_app(target, source)
+
+    assert googleclouddebugger.enable.calls == [
+        pretend.call(module="[MODULE]", version="[VERSION]"),
+    ]
+
+
 def test_debugger_present_with_default_credentials(monkeypatch):
     googleclouddebugger = pretend.stub(
         enable=pretend.call_recorder(lambda *a, **kw: None)
     )
     monkeypatch.setitem(sys.modules, "googleclouddebugger", googleclouddebugger)
+
     googleauthexceptions = pretend.stub(DefaultCredentialsError=pretend.stub())
     monkeypatch.setitem(sys.modules, "google.auth.exceptions", googleauthexceptions)