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Solving Small Problems (Part 2): Reading Cloned Files, Testing, and More

Take a look at how you can solve a variety of small problems, ranging from reading cloned files, adding commit hooks, and more.

· Java Zone

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This post is a continuation of the previous one. Click here to read it, if you haven't done so yet.

Reading Cloned Files

This should be pretty straightforward. It should be enough to use JDK File API and read from the .contents. Let's do this.

Image title

♪♪♪ sounds of coding ♪♪♪

STOP, STOP, STOP!

Didn't you see that? This tiny little PostReader knows too much. The concept .contents directory is specific to the way I'm implementing Git support. I believe we now got a... GitPostReader!

♪♪♪ sounds of coding ♪♪♪

I merged PostReader with GitCloner to achieve a cohesive whole:

@Service
public class GitPostReader {

    /* cloning logic as before */

    public List<Post> readAll() {
        File contentsDir = gitRepository.getWorkTree();
        return Stream.of(contentsDir
                .listFiles(withSupportedExtension()))
                .map(MarkdownPostFactory::create)
                .collect(Collectors.toList());
    }

    private FilenameFilter withSupportedExtension() {
        return (dir, name) -> name.endsWith(MarkdownPostFactory.EXTENSION);
    }

    public Post readOne(String name) {
        File postFile = new File(toPostPath(name));
        if (!postFile.exists()) {
            throw new MissingPostException();
        }
        return MarkdownPostFactory.create(postFile);
    }

    private String toPostPath(String name) {
        return gitRepository.getWorkTree().getPath() + name + MarkdownPostFactory.EXTENSION;
    }
}

The fact that I merged these two classes is not that important. Actually, if there was more logic in each of them, they would probably stay separate. The important point is that PostReader became coupled to Git support, which effectively made it a GitPostReader.

Commit Hook

Adding a commit hook sounds easy. It should be enough to create an endpoint to call a git pull command.

♪♪♪ sounds of coding ♪♪♪

As expected, this one was easy (to write).

@RestController
public class GitController {

    @Autowired
    private GitPostReader gitPostReader;

    @RequestMapping(path = "/git/commit", method = RequestMethod.POST)
    public void postCommit() {
        gitPostReader.pullChanges();
    }
}

In GitPostReader, I created a reference to Git object and added pullChanges method:

@Service
public class GitPostReader {

    /* nothing new */

    private Git git;

    /* nothing new */

    public void pullChanges() {
        git.pull();
    }
}

I have no idea how to test it without leveraging more of JGit APIs. I'm not sure if it's required, since I'm only delegating to JGit. For now, I created an integration test:

@SpringApplicationConfiguration(BloggingPlatform.class)
@WebAppConfiguration
class GitControllerIntegrationSpec extends Specification {

    @Autowired
    WebApplicationContext wac

    MockMvc mockMvc

    def setup() {
        mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build()
    }

    def "post commit hook"() {
        expect:
        mockMvc.perform(post("/git/commit"))
                .andExpect(status().isOk())
    }
}

Testing

Final step, I have to test the whole thing. To be honest, while developing I used the old test. I configured the application to use the hello world repository. Then, I ran it and checked if it fails with a single README post with TILT's and a header.

As before, I'd like to test most cases via integration tests. It makes sense to me that integration tests would use a real, online Git repostory. In this case, it should be enough to move old test posts into an online repo and point my tests to use it. I'll also add a "TILT post" to check that the application doesn't crash in case of missing metadata fields.

♪♪♪ sounds of coding ♪♪♪

As said above, I moved test posts to a special repository. You can see it here.

I modified home test and added special tilt post test. For the "TILT post," I created a special assertTiltPost method.

@SpringApplicationConfiguration(BloggingPlatform.class)
@WebAppConfiguration
@DirtiesContext
class PostControllerIntegrationSpec extends Specification {

    /* nothing new */

    def "home"() {
        expect:
        def result = mockMvc.perform(get("/"))
                .andExpect(status().isOk())
                .andExpect(view().name("home"))
                .andReturn()
        def posts = result.modelAndView.model.posts
        assertTestPost(posts[0], 2)
        assertTestPost(posts[1], 1)
        assertTiltPost(posts[2])
    }

    /* nothing new */

    def "tilt post"() {
        expect:
        def result = mockMvc.perform(get("/tilt"))
                .andExpect(status().isOk())
                .andExpect(view().name("post"))
                .andReturn()
        assertTiltPost(result.modelAndView.model.post)
    }

    /* nothing new */

    void assertTiltPost(post) {
        assert post.title == "TILT"
        assert post.summary == "TILT"
        assert post.date.format(ISO_LOCAL_DATE) == "1970-01-01"
        assert post.url == "/tilt"
        assert post.content == ""
    }
}

When preparing the tests, I found 2 bugs:

  • Git object leaks file handles if not closed
  • I forgot to sort posts when reading all of them for the home page

Well, the test suite has proven itself trustworthy!

That's it!

Oh boy/girl, that was fun! It was also easy, despite the fact that I used a new library and I didn't know how to test the feature at start. Step by step, small problem by small problem, I got the most important feature running in a few hours. If you experienced problems with mental overload during analysis before, you now know what to do — solve small problems!

Before I merge the changes, the application will be available here. Afterwards, it will be available under standard link. If you'd like to read final version of the code, contribute or w/e, project's repository is here.

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Topics:
java ,commit hook ,cloning ,testing

Published at DZone with permission of Grzegorz Ziemoński, DZone MVB. See the original article here.

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