test(examples-fastapi): tidy FastAPI example, making consistent with Flask (#274)

* test(examples-fastapi): tidy FastAPI example, making consistent with Flask

re #270

* test(examples-fastapi): tidy FastAPI example, making consistent with Flask

re #270

* test(examples-fastapi): tidy FastAPI example, making consistent with Flask

re #270

* test(examples-fastapi): tidy FastAPI example, making consistent with Flask

re #270

Author: mikegeeves

Makefile

@@ -94,8 +94,7 @@ messaging:
 
 
 .PHONY: examples
-examples: consumer flask messaging
-# TODO: Fix fastapi, to run all examples this should be: consumer flask fastapi messaging
+examples: consumer flask fastapi messaging
 
 
 .PHONY: package

examples/README.md

@@ -82,6 +82,9 @@ The following file(s) will be created when the tests are run:
 The Flask [Provider] example consists of a basic Flask app, with a single endpoint route.
 This implements the service expected by the [consumer](#consumer).
 
+Functionally, this provides the same service and tests as the [fastapi_provider](#fastapi_provider). Both are included to
+demonstrate how Pact can be used in different environments with different technology stacks and approaches.
+
 The [Provider] side is responsible for performing the tests to verify if it is compliant with the [Pact file] contracts
 associated with it.
 
@@ -132,7 +135,55 @@ The following file(s) will be created when the tests are run
 
 ## fastapi_provider
 
-TODO
+The FastAPI [Provider] example consists of a basic FastAPI app, with a single endpoint route.
+This implements the service expected by the [consumer](#consumer).
+
+Functionally, this provides the same service and tests as the [flask_provider](#flask_provider). Both are included to
+demonstrate how Pact can be used in different environments with different technology stacks and approaches.
+
+The [Provider] side is responsible for performing the tests to verify if it is compliant with the [Pact file] contracts
+associated with it.
+
+As such, the tests use the pact-python Verifier to perform this verification. Two approaches are demonstrated:
+- Testing against the [Pact broker]. Generally this is the preferred approach, see information on [Sharing Pacts].
+- Testing against the [Pact file] directly. If no [Pact broker] is available you can verify against a static [Pact file].
+- 
+### Running
+
+To avoid package version conflicts with different applications, it is recommended to run these tests from a
+[Virtual Environment]
+
+The following commands can be run from within your [Virtual Environment], in the `examples/fastapi_provider`.
+
+To perform the python tests:
+```bash
+pip install -r requirements.txt # Install the dependencies for the FastAPI example
+pip install -e ../../           # Using setup.py in the pact-python root, install any pact dependencies and pact-python
+./run_pytest.sh                 # Wrapper script to first run FastAPI, and then run the tests
+```
+
+To perform verification using CLI to verify the [Pact file] against the FastAPI [Provider] instead of the python tests:
+```bash
+pip install -r requirements.txt # Install the dependencies for the FastAPI example
+./verify_pact.sh                # Wrapper script to first run FastAPI, and then use `pact-verifier` to verify locally
+```
+
+To perform verification using CLI, but verifying the [Pact file] previously provided by a [Consumer], and publish the
+results. This example requires that the [Pact broker] is already running, and the [Consumer] tests have been published
+already, described in the [consumer](#consumer) section above.
+```bash
+pip install -r requirements.txt # Install the dependencies for the FastAPI example
+./verify_pact.sh 1              # Wrapper script to first run FastAPI, and then use `pact-verifier` to verify and publish
+```
+
+### Output
+
+The following file(s) will be created when the tests are run
+
+| Filename                      | Contents  |
+|-------------------------------| ----------|
+| fastapi_provider/log/pact.log | All Pact interactions with the FastAPI Provider. Every interaction example retrieved from the Pact Broker will be performed during the Verification test; the request/response logged here. | 
+
 
 ## message
 
@@ -153,4 +204,4 @@ without a [Pact Broker].
 [Pact verification]: https://docs.pact.io/getting_started/terminology#pact-verification]
 [Virtual Environment]: https://docs.python.org/3/tutorial/venv.html
 [Sharing Pacts]: https://docs.pact.io/getting_started/sharing_pacts/]
-[How to Run a Flask Application]: https://www.twilio.com/blog/how-run-flask-application
+[How to Run a Flask Application]: https://www.twilio.com/blog/how-run-flask-application

examples/fastapi_provider/pythonclient-pythonservice.json

@@ -2,3 +2,4 @@ fastapi==0.67.0
 pytest==5.4.1
 requests>=2.26.0
 uvicorn>=0.14.0
+testcontainers==3.3.0

examples/fastapi_provider/requirements.txt

@@ -1,15 +1,6 @@
 #!/bin/bash
 set -o pipefail
 
-uvicorn src.provider:app --host 0.0.0.0 --port 8080 & &>/dev/null
-FASTAPI_PID=$!
-
-function teardown {
-  echo "Tearing down FastAPI server: ${FASTAPI_PID}"
-  kill -9 $FLASK_PID
-}
-trap teardown EXIT
-
-sleep 1
-
-pytest
+# Unlike in the Flask example, here the FastAPI service is started up as a pytest fixture. This is then including the
+# main and pact routes via fastapi_provider.py to run the tests against
+pytest --run-broker True --publish-pact 1

examples/fastapi_provider/run_pytest.sh

@@ -1,14 +1,25 @@
+import logging
+
 from fastapi import FastAPI, HTTPException, APIRouter
+from fastapi.logger import logger
 
 fakedb = {}  # Use a simple dict to represent a database
+
+logger.setLevel(logging.DEBUG)
 router = APIRouter()
 app = FastAPI()
 
 
 @app.get("/users/{name}")
 def get_user_by_name(name: str):
+    """Handle requests to retrieve a single user from the simulated database.
+
+    :param name: Name of the user to "search for"
+    :return: The user data if found, HTTP 404 if not
+    """
     user_data = fakedb.get(name)
     if not user_data:
+        logger.error(f"GET user for: '{name}', HTTP 404 not found")
         raise HTTPException(status_code=404, detail="User not found")
-
+    logger.error(f"GET user for: '{name}', returning: {user_data}")
     return user_data

examples/fastapi_provider/src/provider.py

@@ -1,11 +1,105 @@
+import pathlib
+import sys
+from multiprocessing import Process
+
+import docker
+import pytest
+from testcontainers.compose import DockerCompose
+
+from .pact_provider import run_server
+
+
+@pytest.fixture(scope="module")
+def server():
+    proc = Process(target=run_server, args=(), daemon=True)
+    proc.start()
+    yield proc
+
+    # Cleanup after test
+    if sys.version_info >= (3, 7):
+        # multiprocessing.kill is new in 3.7
+        proc.kill()
+    else:
+        proc.terminate()
+
 
 def pytest_addoption(parser):
     parser.addoption(
-        "--publish-pact", type=str, action="store",
-        help="Upload generated pact file to pact broker with version"
+        "--publish-pact", type=str, action="store", help="Upload generated pact file to pact broker with version"
     )
 
-    parser.addoption(
-        "--provider-url", type=str, action="store",
-        help="The url to our provider."
+    parser.addoption("--run-broker", type=bool, action="store", help="Whether to run broker in this test or not.")
+
+
+@pytest.fixture(scope="session", autouse=True)
+def publish_existing_pact(broker):
+    """Publish the contents of the pacts folder to the Pact Broker.
+
+    In normal usage, a Consumer would publish Pacts to the Pact Broker after
+    running tests - this fixture would NOT be needed.
+    .
+    Because the broker is being used standalone here, it will not contain the
+    required Pacts, so we must first spin up the pact-cli and publish them.
+
+    In the Pact Broker logs, this corresponds to the following entry:
+      PactBroker::Pacts::Service -- Creating new pact publication with params \
+      {:consumer_name=>"UserServiceClient", :provider_name=>"UserService", \
+      :revision_number=>nil, :consumer_version_number=>"1", :pact_version_sha=>nil, \
+      :consumer_name_in_pact=>"UserServiceClient", :provider_name_in_pact=>"UserService"}
+    """
+    source = str(pathlib.Path.cwd().joinpath("..", "pacts").resolve())
+    pacts = [f"{source}:/pacts"]
+    envs = {
+        "PACT_BROKER_BASE_URL": "http://broker_app:9292",
+        "PACT_BROKER_USERNAME": "pactbroker",
+        "PACT_BROKER_PASSWORD": "pactbroker",
+    }
+
+    client = docker.from_env()
+
+    print("Publishing existing Pact")
+    client.containers.run(
+        remove=True,
+        network="broker_default",
+        volumes=pacts,
+        image="pactfoundation/pact-cli:latest",
+        environment=envs,
+        command="publish /pacts --consumer-app-version 1",
     )
+    print("Finished publishing")
+
+
+# This fixture is to simulate a managed Pact Broker or Pactflow account.
+# For almost all purposes outside this example, you will want to use a real
+# broker. See https://github.com/pact-foundation/pact_broker for further details.
+@pytest.fixture(scope="session", autouse=True)
+def broker(request):
+    version = request.config.getoption("--publish-pact")
+    publish = True if version else False
+
+    # If the results are not going to be published to the broker, there is
+    # nothing further to do anyway
+    if not publish:
+        yield
+        return
+
+    run_broker = request.config.getoption("--run-broker")
+
+    if run_broker:
+        # Start up the broker using docker-compose
+        print("Starting broker")
+        with DockerCompose("../broker", compose_file_name=["docker-compose.yml"], pull=True) as compose:
+            stdout, stderr = compose.get_logs()
+            if stderr:
+                print("Errors\\n:{}".format(stderr))
+            print("{}".format(stdout))
+            print("Started broker")
+
+            yield
+            print("Stopping broker")
+        print("Broker stopped")
+    else:
+        # Assuming there is a broker available already, docker-compose has been
+        # used manually as the --run-broker option has not been provided
+        yield
+        return