Merge pull request #1 from pact-foundation/initial-framework

Initial pact-python implementation

Author: matthewbalvanz-wf

.gitignore

@@ -1,3 +1,6 @@
+# pact-python specific ignores
+e2e/pacts
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

CHANGES.txt

@@ -0,0 +1 @@
+v0.1.0, 2017-03-30 -- Basic support for authoring contracts against a separately running mock service

MANIFEST.in

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+include LICENSE
+include *.txt
+include *.md
+prune *test

Makefile

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+DOCS_DIR := ./docs
+
+define VERSION_CHECK
+import setup
+import pact
+msg = 'pact.__version__ must match the last version in CHANGES.txt'
+assert setup.get_version() == pact.__version__, msg
+endef
+
+
+help:
+	@echo ""
+	@echo "  deps       to install the required files for development"
+	@echo "  package    to create a distribution package in /dist/"
+	@echo "  release    to perform a release build, including deps, test, and package targets"
+	@echo "  test       to run all tests"
+	@echo ""
+
+
+.PHONY: release
+release: deps test package
+
+
+.PHONY: deps
+deps:
+	pip install -r requirements_dev.txt
+
+
+.PHONY: e2e
+e2e:
+	sh -c '\
+		cd e2e; \
+		docker-compose pull > /dev/null; \
+		docker-compose up -d pactmockservice; \
+		while ! nc -z localhost 1234; do sleep 0.1; done; \
+		docker-compose logs --follow > ./pacts/mock-service-logs.txt & \
+		nosetests ./contracts; \
+		docker-compose down; \
+		docker-compose up -d app pactverifier; \
+		docker-compose logs --follow >> ./pact/verifier-logs.txt & \
+		docker-compose exec pactverifier bundle exec rake verify_pacts; \
+		docker-compose down'
+
+.PHONY: package
+package:
+	python setup.py sdist
+
+
+export VERSION_CHECK
+.PHONY: test
+test: deps
+	@echo "Checking version consistency..."
+	python -c "$$VERSION_CHECK"
+
+	@echo "flake8..."
+	flake8
+
+	@echo "pydocstyle..."
+	pydocstyle pact
+
+	@echo "testing..."
+	tox

README.md

@@ -1,2 +1,297 @@
 # pact-python
-Python version of Pact. Enables consumer driven contract testing, providing a mock service and DSL for the consumer project, and interaction playback and verification for the service provider project.
+Python version of Pact. Enables consumer driven contract testing,
+providing a mock service and DSL for the consumer project, and
+interaction playback and verification for the service provider project.
+
+For more information about what Pact is, and how it can help you
+test your code more efficiently, check out the [Pact documentation].
+
+# How to use pact-python
+
+## Installation
+```
+pip install pact-python
+```
+
+## Writing a Pact
+Creating a complete contract is a two step process:
+
+1. Create a test on the consumer side that declares the expectations it has of the provider
+2. Create a provider state that allows the contract to pass when replayed against the provider
+
+## Writing the Consumer Test
+
+If we have a method that communicates with one of our external services, which we'll call
+`Provider`, and our product, `Consumer` is hitting an endpoint on `Provider` at
+`/users/<user>` to get information about a particular user.
+
+If the code to fetch a user looked like this:
+
+```python
+import requests
+
+
+def user(user_name):
+    """Fetch a user object by user_name from the server."""
+    uri = 'http://localhost:1234/users/' + user_name
+    return requests.get(uri).json()
+```
+
+Then `Consumer`'s contract test might look something like this:
+
+```python
+import unittest
+
+from pact import Consumer, Provider
+
+
+class GetUserInfoContract(unittest.TestCase):
+  def test_get_user(self):
+    pact = Consumer('Consumer').has_pact_with(Provider('Provider'))
+    expected = {
+      'username': 'UserA',
+      'id': 123,
+      'groups': ['Editors']
+    }
+      
+    (pact
+     .given('UserA exists and is not an administrator')
+     .upon_receiving('a request for UserA')
+     .with_request('get', '/users/UserA')
+     .will_respond_with(200, body=expected))
+
+    with pact:
+      result = user('UserA')
+    
+    self.assertEqual(result, expected)
+
+```
+
+This does a few important things:
+
+ - Defines the Consumer and Provider objects that describe our product and our service under test
+ - Uses `given` to define the setup criteria for the Provider `UserA exists and is not an administrator`
+ - Defines what the request that is expected to be made by the consumer will contain
+ - Defines how the server is expected to respond
+
+Using the Pact object as a [context manager], we call our method under test
+which will then communicate with the Pact mock service. The mock service will respond with
+the items we defined, allowing us to assert that the method processed the response and
+returned the expected value.
+
+The default hostname and port for the Pact mock service will be
+`localhost:1234` but you can adjust this during Pact creation:
+
+```python
+from pact import Consumer, Provider
+pact = Consumer('Consumer').has_pact_with(
+    Provider('Provider'), host_name='mockservice', port=8080)
+```
+
+This can be useful if you are running your tests and the mock service inside a Docker
+network, where you want to reference the service by its Docker name, instead of via
+the `localhost` interface. It is important to note that the code you are testing with
+this contract _must_ contact the mock service. So in this example, the `user` method
+could accept an argument to specify the location of the server, or retrieve it from an
+environment variable so you can change its URI during the test. Another option is to
+specify a Docker network alias so the requests that you make will go to the container.
+
+The mock service offers you several important features when building your contracts:
+- It provides a real HTTP server that your code can contact during the test and provides the responses you defined.
+- You provide it with the expectations for the request your code will make and it will assert the contents of the actual requests made based on your expectations.
+- If a request is made that does not match one you defined or if a request from your code is missing it will return an error with details.
+- Finally, it will record your contracts as a JSON file that you can store in your repository or publish to a Pact broker.
+
+## Expecting Variable Content
+The above test works great if that user information is always static, but what happens if
+the user has a last updated field that is set to the current time every time the object is
+modified? To handle variable data and make your tests more robust, there are 3 helpful matchers:
+
+### Term(matcher, generate)
+Asserts the value should match the given regular expression. You could use this
+to expect a timestamp with a particular format in the request or response where
+you know you need a particular format, but are unconcerned about the exact date:
+
+```python
+from pact import Term
+...
+body = {
+    'username': 'UserA',
+    'last_modified': Term('\d+-\d+-\d+T\d+:\d+:\d+', '2016-12-15T20:16:01')
+}
+
+(pact
+ .given('UserA exists and is not an administrator')
+ .upon_receiving('a request for UserA')
+ .with_request('get', '/users/UserA/info')
+ .will_respond_with(200, body=body))
+```
+
+When you run the tests for the consumer, the mock service will return the value you provided
+as `generate`, in this case `2016-12-15T20:16:01`. When the contract is verified on the
+provider, the regex will be used to search the response from the real provider service
+and the test will be considered successful if the regex finds a match in the response.
+
+### SomethingLike(matcher)
+Asserts the element's type matches the matcher. For example:
+
+```python
+from pact import SomethingLike
+SomethingLike(123)  # Matches if the value is an integer
+SomethingLike('hello world')  # Matches if the value is a string
+SomethingLike(3.14)  # Matches if the value is a float
+```
+
+The argument supplied to `SomethingLike` will be what the mock service responds with.
+
+### EachLike(matcher, minimum=None, maximum=None)
+Asserts the value is an array type that consists of elements
+like the ones passed in. It can be used to assert simple arrays:
+
+```python
+from pact import EachLike
+EachLike(1)  # All items are integers
+EachLike('hello')  # All items are strings
+```
+
+Or other matchers can be nested inside to assert more complex objects:
+
+```python
+from pact import EachLike, SomethingLike, Term
+EachLike({
+    'username': Term('[a-zA-Z]+', 'username'),
+    'id': SomethingLike(123),
+    'groups': EachLike('administrators')
+})
+```
+
+> Note, you do not need to specify everything that will be returned from the Provider in a
+> JSON response, any extra data that is received will be ignored and the tests will still pass.
+
+For more information see [Matching](https://docs.pact.io/documentation/matching.html)
+
+## Running the Mock Service
+This library does not yet automatically handle running the [Pact Mock Service] so you will need to
+start that manually before running the tests. There are two primary ways to run the mock service:
+
+1. [Install it and run it using Ruby](https://github.com/bethesque/pact-mock_service#usage)
+2. Run it as a Docker container
+
+Using the Docker container additionally has two options. You can run it via the `docker` command:
+
+```
+docker run -d -p "1234:1234" -v /tmp/log:/var/log/pacto -v $(pwd)/contracts:/opt/contracts madkom/pact-mock-service
+```
+
+Which will start the service and expose it as port `1234` on your computer, mount
+`/tmp/log` on your machine to house the mock service log files, and the directory
+`contracts` in the current working directory to house the contracts when they are published.
+
+Additionally, you could run the mock service using `docker-compose`:
+
+```yaml
+version: '2'
+services:
+  pactmockservice:
+    image: madkom/pact-mock-service
+    ports:
+      - "1234:1234"
+    volumes:
+      - /tmp/pact:/var/log/pacto
+      - ./contracts:/opt/contracts
+```
+
+> Note: How you run the mock service may change what hostname and port you should
+> use when running your consumer tests. For example: If you change the host port on
+> the command line to be `8080`, your tests would need to contact `localhost:8080`.
+
+## Verifying Pacts Against a Service
+> pact-python does not yet have any involvement in the process of verifying a contract against
+> a provider. This section is included to provide insight into the full cycle of a
+> contract for those getting started.
+
+Like the mock service, the provider verifier can be run in two ways:
+
+1. [Install and use it as a Ruby application][pact-provider-verifier]
+2. Run it as a Docker container
+
+> Both choices have very similar configuration options. We will illustrate the Docker
+> method below, but the Ruby method supports the same features.
+
+When verifying your contracts, you may find it easier to run the provider application
+and the verifier in separate Docker containers. This gives you a nice isolated
+network, where you can set the DNS records of the services to anything you desire
+and not have to worry about port conflicts with other services on your computer.
+Launching the provider verifier in a `docker-compose.yml` might look like this:
+
+```yaml
+version: '2'
+services:
+  app:
+    image: the-provider-application-to-test
+
+  pactverifier:
+    command: ['tail', '-f', '/dev/null']
+    image: dius/pact-provider-verifier-docker
+    depends_on:
+      - app
+    volumes:
+      - ./contracts:/tmp/pacts
+    environment:
+      - pact_urls=/tmp/pacts/consumer-provider.json
+      - provider_base_url=http://app
+      - provider_states_url=http://app/_pact/provider-states
+      - provider_states_active_url=http://app/_pact/provider-states/active
+```
+
+In this example, our `app` container may take a few moments to start, so we don't
+immediately start running the verification, and instead `tail -f /dev/null` which will keep
+the container running forever. We can then use `docker-compose` to run the tests like so:
+
+```
+docker-compose up -d
+# Insert code to check that `app` has finished starting and is ready for requests
+docker-compose exec pactverifier bundle exec rake verify_pacts
+```
+
+You configure the verifier in Docker using 4 environment variables:
+- `pact_urls` - a comma delimited list of pact file urls
+- `provider_base_url` - the base url of the pact provider
+- `provider_states_url` - the full url of the endpoint which returns provider states by consumer
+- `provider_states_active_url` - the full url of the endpoint which sets the active pact consumer and provider state
+
+### Provider States
+In many cases, your contracts will need very specific data to exist on the provider
+to pass successfully. If you are fetching a user profile, that user needs to exist,
+if querying a list of records, one or more records needs to exist. To support
+decoupling the testing of the consumer and provider, Pact offers the idea of provider
+states to communicate from the consumer what data should exist on the provider.
+
+When setting up the testing of a provider you will also need to setup the management of
+these provider states. The Pact verifier does this by making additional HTTP requests to
+the `provider_states_url` and `provider_stats_active_url` you provide. These URLs could be
+on the provider application or a separate one. Some strategies for managing state include:
+
+- Having endpoints in your application that are not active in production that create and delete your datastore state
+- A separate application that has access to the same datastore to create and delete, like a separate App Engine module or Docker container pointing to the same datastore
+- A standalone application that can start and stop the other server with different datastore states
+
+For more information about provider states, refer to the [Pact documentation] on [Provider States].
+
+# Development
+Please read [CONTRIBUTING.md](.github/CONTRIBUTING.md)
+
+Create a Python virtualenv for use with this project
+`make release`
+
+## Testing
+Unit: `make test`
+
+End to end: `make e2e`
+
+[context manager]: https://en.wikibooks.org/wiki/Python_Programming/Context_Managers
+[Pact]: https://www.gitbook.com/book/pact-foundation/pact/details
+[Pact documentation]: https://docs.pact.io/
+[Pact Mock Service]: https://github.com/bethesque/pact-mock_service
+[Provider States]: https://docs.pact.io/documentation/provider_states.html
+[pact-provider-verifier]: https://github.com/pact-foundation/pact-provider-verifier