I have built a "sidecar" to my micro services, to perform common monitoring and logging services.
So, i have the sidecar library that basically works by the "template method" pattern and I have a ring middleware that wrapps the calls to my services through the sidecar and it works... But i would like to remove the dependency on ring.
So, my question:
Is there a way to intercept the calls from ring to my API-functions and wrapp it without adding knowledge to neither ring or my API. Simply put, intercept calls to a random named function and replace it with my own.
I believe you can use https://github.com/technomancy/robert-hooke to do this
Related
As there is an initialize function, is there an exit/on_exit function such as I can close my database connection into it?
I would suggest to handle this at the request level to be fully portable among various EiffelWeb connectors.
Now, could you tell us which solution you are using ? EiffelWeb standalone connector, or rather libfcgi with apache for instance? or else?
For standalone, you can redefine the "launch" procedure, in order to perform cleanup task when you exit the application (which is also the server).
For libfcgi, the C API may provide such facility, but so far, the Eiffel libfcgi library does not wrap it. If needed this may be possible to implement it.
Called in each request which is probably not the best solution but I have chosen following way for the moment:
Redefine the clean procedure of WSF_FILTERED_ROUTED_EXECUTION inherited into the classical EWF_APP_EXECUTION to close the connection
Connect into the redefined initialize
I'm writing a Gradle plugin that interacts with an external HTTP API. This interaction is handled by a single class (let's call it ApiClient). I'm writing some high-level tests that use Gradle TestKit to simulate an entire build that uses the plugin, but I obviously don't want them to actually hit the API. Instead, I'd like to mock ApiClient and check that its methods have been called with the appropriate arguments, but I'm not sure how to actually inject the mocked version into the plugin. The plugin is instantiated somewhere deep within Gradle, and gets applied to the project being executed using its void apply(Project project) method, so there doesn't appear to be a way to inject a MockApiClient object.
Perhaps one way is to manually instantiate a Project, apply() the plugin to it (at which point, I can inject the mocked object because I have control over plugin instantiation), and then programmatically execute a task on the project, but how can I do that? I've read the Gradle API documentation and haven't seen an obvious way.
A worst-case solution will be to pass in a debug flag through the plugin extension configuration, which the plugin will then use to determine whether it should use the real ApiClient or a mock (which would print some easily grep-able messages to the STDOUT). This isn't ideal, though, since it's more fuzzy than checking the arguments actually passed to the ApiClient methods.
Perhaps you could split your plugin into a few different plugins
my-plugin-common - All the common stuff
my-plugin-real-services - Adds the "real" services to the model (eg RealApiClient)
my-plugin-mock-services - Adds "mock" services to the model (eg MockApiClient)
my-plugin - Applies my-plugin-real-services and my-plugin-common
my-plugin-mock - Applies my-plugin-mock-services and my-plugin-common
In the real world, people will only ever apply: 'my-plugin'
For testing you could apply: 'my-plugin-mock'
As title, when to use httptest.Server and httptest.ResponseRecorder?
It seems to me that I can also test my handlers to return correct response using httptest.Server. I can simply start a httptest.Server given with my implementation of handlers, then do validations on the response's body.
Please correct if I'm wrong, I am learning Go + TDD
When you just want to check, if your http.Handler does what it should, you don't need to use httptest.Server. Just call your handler with an httptest.ResponseRecorder instance and check the output as in the example.
The possible uses of httptest.Server are numerous, so here are just a couple that come to my mind:
If your code depends on some external services and APIs, you can use a test server to emulate them. (Although I personally would isolate all code dealing with external data sources and then use them through interfaces, so that I could easily create fake objects for my tests.)
If you work on a client-server application, you can use a test server to emulate the server-side when testing the client-side.
I have a service reference to a .NET 2.0 web service. I have a reference to this service in my repository and I want to move to Ninject. I've been using DI for some time now, but haven't tried it with a web service like this.
So, in my code, the repository constructor creates two objects: the client proxy for the service, and an AuthHeader object that is the first parameter of every method in the proxy.
The AuthHeader is where I'm having friction. Because the concrete type is required as the first parameter on every call in the proxy, I believe I need to take a dependency on AuthHeader in my repository. Is this true?
I extracted an interface for AuthHeader from my reference.cs. I wanted to move to the following for my repository constructor:
[Inject]
public PackageRepository(IWebService service, IAuthHeader authHeader)
{
_service = service;
_authHeader = authHeader;
}
...but then I can't make calls to my service proxy like
_service.MakeSomeCall(_authheader, "some value").
...because because MakeSomeCall is expecting an AuthHeader, not an IAuthHeader.
Am I square-pegging a round hole here? Is this just an area where there isn't a natural fit (because of web service "awesomeness")? Am I missing an approach?
It's difficult to understand exactly what the question is here, but some general advice might be relevant to this situation:
Dependency injection does not mean that everything has to be an interface. I'm not sure why you would try to extract an interface from a web service proxy generated from WSDL; the types in the WSDL are contracts which you must follow. This is especially silly if the IAuthHeader doesn't have any behaviour (it doesn't seem to) and you'll never have alternate implementations.
The reason why this looks all wrong is because it is wrong; this web service is poorly-designed. Information that's common to all messages (like an authentication token) should never go in the body where it translates to a method parameter; instead it should go in the message header, wherethe ironically-named AuthHeader clearly isn't. Headers can be intercepted by the proxy and inspected prior to executing any operation, either on the client or service side. In WCF that's part of the behavior (generally ClientCredentials for authentication) and in legacy WSE it's done as an extension. Although it's theoretically possible to do this with information in the message body, it's far more difficult to pull off reliably.
In any event, what's really important here isn't so much what your repository depends on but where that dependency comes from. If your AuthHeader is injected by the kernel as a dependency then you're still getting all the benefits of DI - in particular the ability to have this all registered in one place or substitute a different implementation (i.e. a derived class).
So design issues aside, I don't think you have a real problem in your DI implementation. If the class needs to take an AuthHeader then inject an AuthHeader. Don't worry about the exact syntax and type, as long as it takes that dependency as a constructor argument or property.
I have some written a number of unit tests that test a wrapper around a FTP server API.
Both the unit tests and the FTP server are on the same machine.
The wrapper API gets deployed to our platform and are used in both remoting and web service scenarios. The wrapper API essentially takes XML messages to perform tasks such as adding/deleting/updating users, changing passwords, modifying permissions...that kinda thing.
In a unit test, say to add a user to a virtual domain, I create the XML message to send to the API. The API does it's work and returns a response with status information about whether the operation was successful or failed (error codes, validation failures etc).
To verify whether the API wrapper code really did do the right thing (if the response indicated success), I invoke the FTP server's COM API and query its store directly to see if, for example when creating a user account, the user account really did get created.
Does this smell bad?
Update 1: #Jeremy/Nick: The wrapper is the focus of the testing, the FTP server and its COM API are 3rd party products, presumably well tested and stable. The wrapper API has to parse the XML message and then invoke the FTP server's API. How would I verify, and this may be a silly case, that a particular property of the user account is set correctly by the wrapper. For example setting the wrong property or attribute of an FTP account due to a typo in the wrapper code. A good example being setting the upload and download speed limits, these may get transposed in the wrapper code.
Update 2: thanks all for the answers. To the folks who suggested using mocks, it had crossed my mind, but the light hasn't switched on there yet and I'm still struggling to get my head round how I would get my wrapper to work with a mock of the FTP server. Where would the mocks reside and do I pass an instance of said mocks to the wrapper API to use instead of calling the COM API? I'm aware of mocking but struggling to get my head round it, mostly because I find most of the examples and tutorials are so abstract and (I'm ashamed to say) verging on the incomprehensible.
You seem to be mixing unit & component testing concerns.
If you're unit-testing your wrapper, you should use a mock FTP server and don't involve the actual server. The plus side is, you can usually achieve 100% automation like this.
If you're component-testing the whole thing (the wrapper + FTP server working together), try to verify your results at the same level as your tests i.e. by means of your wrapper API. For example, if you issue a command to upload a file, next, issue a command to delete/download that file to make sure that the file was uploaded correctly. For more complex operations where it's not trivial to test the outcome, then consider resorting to the COM API "backdoor" you mentioned or perhaps involve some manual verification (do all of your tests need to be automated?).
To verify whether the API wrapper code really did do the right thing (if the response indicated success), I invoke the FTP server's COM API
Stop right there. You should be mocking the FTP server and the wrapper should operate against the mock.
If your test runs both the wrapper and the FTP server, you are not Unit Testing.
To test your wrapper with a mock object, you can do the following:
Write a COM object that has the same interface as the FTP server's COM API. This will be your mock object. You should be able to interchange the real FTP server and your mock object by passing the interface pointer of either to your wrapper by means of dependency injection.
Your mock object should implement hard-coded behaviour based on the methods called on its interface (which mimics FTP server API) and also based on the argument values used:
For example, if you have an UploadFile method you can blindly return a success result and perhaps store the file name that was passed in in an array of strings.
You could simulate an upload error when you encounter a file name with "error" in it.
You could simulate latency/timeout when you encounter a file name with "slow" in it.
Later on, the DownloadFile method could check the internal string array to see if a file with that name was already "uploaded".
The pseudo-code for some test cases would be:
//RealServer theRealServer;
//FtpServerIntf ftpServerIntf = theRealServer.getInterface();
// Let's test with our mock instead
MockServer myMockServer;
FtpServerIntf ftpServerIntf = myMockServer.getInterface();
FtpWrapper myWrapper(ftpServerIntf);
FtpResponse resp = myWrapper.uploadFile("Testing123");
assertEquals(FtpResponse::OK, resp);
resp = myWrapper.downloadFile("Testing123");
assertEquals(FtpResponse::OK, resp);
resp = myWrapper.downloadFile("Testing456");
assertEquals(FtpResponse::NOT_FOUND, resp);
resp = myWrapper.downloadFile("SimulateError");
assertEquals(FtpResponse::ERROR, resp);
I hope this helps...
I agree with Nick and Jeremy about not touching the API. I would look at mocking the API.
http://en.wikipedia.org/wiki/Mock_object
If it's .NET you can use:
Moq: http://code.google.com/p/moq/
And a bunch of other mocking libraries.
What are you testing the wrapper or the API. The API should work as is, so you don't need to test it I would think. Focus your testing efforts on the wrapper and pretend like the API doesn't exist, when I write a class that does file access I don't unit test the build in streamreader...I focus on my code.
I would say your API should be treated just like a database or a network connection when testing. Don't test it, it isn't under your control.
It doesn't sound like you're asking "Should I test the API?" — you're asking "Should I use the API to verify whether my wrapper is doing the right thing?"
I say yes. Your unit tests should assert that your wrapper passes along the information reported by the API. In the example you give, for instance, I don't know how you would avoid touching the API. So I don't think it smells bad.
The only time I can think of when it might make sense to dip into the lower level API to verify results if if the higher-level API is write-only. For example, if you can create a user using the high-level API, then there should be a high-level API to get the user accounts, too. Use that.
Other folks have suggested mocking the lower-level API. That's good, if you can do it. If the lower-level component is mocked, checking the mocks to make sure the right state is set should be okay.