Getting Information About Your Git Repository With C#

During a hackathon not so long ago, I wanted to incorporate some source control data into my .NET assembly version information for the purposes of troubleshooting installations, making it easier for people to report the code in which they found a bug, and making it easier for people to find the code in which a bug was found1. The plan was to automatically encode the branch, the commit hash, and whether there were local commits or local changes into the `AssemblyConfiguration` attribute of my assemblies during the build.

At the time, I hacked together the `RepositoryInformation` class below that wraps the command line tool to extract the required information. This class supported detecting if the directory is a repository, checking for local commits and changes, getting the branch name and the name of the upstream branch, and enumerating the log. Though it felt a little wrong just wrapping the command line (and seemed pretty fragile too), it worked. Unfortunately, it was dependent on git being installed on the build system; I would prefer the build to get everything it needs using package management like NuGet and npm2.

class RepositoryInformation : IDisposable
{
    public static RepositoryInformation GetRepositoryInformationForPath(string path, string gitPath = null)
    {
        var repositoryInformation = new RepositoryInformation(path, gitPath);
        if (repositoryInformation.IsGitRepository)
        {
            return repositoryInformation;
        }
        return null;
    }
    
    public string CommitHash
    {
        get
        {
            return RunCommand("rev-parse HEAD");
        }
    }
    
    public string BranchName
    {
        get
        {
            return RunCommand("rev-parse --abbrev-ref HEAD");
        }
    }
    
    public string TrackedBranchName
    {
        get
        {
            return RunCommand("rev-parse --abbrev-ref --symbolic-full-name @{u}");
        }
    }
    
    public bool HasUnpushedCommits
    {
        get
        {
            return !String.IsNullOrWhiteSpace(RunCommand("log @{u}..HEAD"));
        }
    }
    
    public bool HasUncommittedChanges
    {
        get
        {
            return !String.IsNullOrWhiteSpace(RunCommand("status --porcelain"));
        }
    }
    
    public IEnumerable<string> Log
    {
        get
        {
            int skip = 0;
            while (true)
            {
                string entry = RunCommand(String.Format("log --skip={0} -n1", skip++));
                if (String.IsNullOrWhiteSpace(entry))
                {
                    yield break;
                }
                
                yield return entry;
            }
        }
    }
    
    public void Dispose()
    {
        if (!_disposed)
        {
            _disposed = true;
            _gitProcess.Dispose();
        }
    }
    
    private RepositoryInformation(string path, string gitPath)
    {
        var processInfo = new ProcessStartInfo
        {
            UseShellExecute = false,
            RedirectStandardOutput = true,
            FileName = Directory.Exists(gitPath) ? gitPath : "git.exe",
            CreateNoWindow = true,
            WorkingDirectory = (path != null && Directory.Exists(path)) ? path : Environment.CurrentDirectory
        };
        
        _gitProcess = new Process();
        _gitProcess.StartInfo = processInfo;
    }
    
    private bool IsGitRepository
    {
        get
        {
            return !String.IsNullOrWhiteSpace(RunCommand("log -1"));
        }
    }
    
    private string RunCommand(string args)
    {
        _gitProcess.StartInfo.Arguments = args;
        _gitProcess.Start();
        string output = _gitProcess.StandardOutput.ReadToEnd().Trim();
        _gitProcess.WaitForExit();
        return output;
    }
    
    private bool _disposed;
    private readonly Process _gitProcess;
}

If I were to approach this again today, I would use the LibGit2Sharp NuGet package or something similar3. Below is an updated version of `RepositoryInformation` that uses LibGit2Sharp instead of git command line. Clearly, you could forego any type of wrapper for LibGit2Sharp and I probably would if I were incorporating this into a bigger task like the one I originally had planned.

class RepositoryInformation : IDisposable
{
    public static RepositoryInformation GetRepositoryInformationForPath(string path)
    {
        if (LibGit2Sharp.Repository.IsValid(path))
        {
            return new RepositoryInformation(path);
        }
        return null;
    }
    
    public string CommitHash
    {
        get
        {
            return _repo.Head.Tip.Sha;
        }
    }
    
    public string BranchName
    {
        get
        {
            return _repo.Head.Name;
        }
    }
    
    public string TrackedBranchName
    {
        get
        {
            return _repo.Head.IsTracking ? _repo.Head.TrackedBranch.Name : String.Empty;
        }
    }
    
    public bool HasUnpushedCommits
    {
        get
        {
            return _repo.Head.TrackingDetails.AheadBy > 0;
        }
    }
    
    public bool HasUncommittedChanges
    {
        get
        {
            return _repo.RetrieveStatus().Any(s => s.State != FileStatus.Ignored);
        }
    }
    
    public IEnumerable<Commit> Log
    {
        get
        {
            return _repo.Head.Commits;
        }
    }
    
    public void Dispose()
    {
        if (!_disposed)
        {
            _disposed = true;
            _repo.Dispose();
        }
    }
    
    private RepositoryInformation(string path)
    {
        _repo = new Repository(path);
    }

    private bool _disposed;
    private readonly Repository _repo;
}

I have yet to use any of this outside of my hackathon work or this blog entry, but now that I have resurrected it from my library of coding exploits past to write about, I might just resurrect the original plans I had too. Whether that happens or not, I hope you found this useful or at least a little interesting; if so, or if you have some suggestions related to this post, please let me know in the comments.

  1. Sometimes, like a squirrel, you want to know which branch you were on []
  2. I had looked at NuGet packages when I was working on the original hackathon project, but had decided not to use one for some reason or another (perhaps the available packages did not do everything I wanted at that time) []
  3. PowerShell could be a viable replacement for my initial approach, but it would suffer from the same issue of needing git on the build system; by using a NuGet package, the build includes everything it needs []

Five things to love about modern.IE

You might be surprised to learn that the browser testing resources website, modern.IE (provided by Microsoft) is not just about Internet Explorer. Although some of the features are geared solely toward IE testing, some are browser-agnostic and can be very useful when developing websites. Here are a few of the things modern.IE can do for you.

Virtual Machines

Download virtual machines

Working on websites often means debugging using different browser variants. Unless you are exceedingly lucky, that will include older versions of Internet Explorer. While services like BrowserStack are invaluable for testing, they cost money and are not always responsive enough for productive debugging. Instead, I have found virtual machines (VM) to be much more useful.

Microsoft has been making VM's available for Internet Explorer testing via the website modern.IE for quite some time now. You can download VM's for whatever development platform you have, whether it is OS/X, Windows, or Linux.

Available versions of Internet Explorer
Available versions of Internet Explorer
Select virtual machine platform
Select virtual machine platform

Azure RemoteApp

If you want to test your work against the latest Internet Explorer in Windows 10 and you do not want to download a virtual machine, or are working from an unsupported device, Azure RemoteApp is for you.

Azure RemoteApp

All you need is a Microsoft Live ID and you can login and test with the latest IE for free.

Browser Screenshots

Browser Screenshots

Just want to check what your site looks like across various browsers and devices? The Browser Screenshots feature of modern.IE will give you screenshots across nine common browsers and devices. Somewhat surprisingly (at least to me), this includes more than just Internet Explorer; at the time of writing, you get:

  • Internet Explorer 11.0 Desktop on Windows 8.1
  • Opera 12.16 on Windows 8.1
  • Android Browser on Samsung Galaxy S3
  • Android Browser on Nexus 7
  • Mobile Safari on iPhone 6
  • Safari 7.0 on OS X Mavericks
  • Chrome 36.0 on Windows 8.1
  • Firefox 30.0 on Windows 8.1
  • Mobile Safari on iPad Air

Not only will it give you the screenshots, but you can share them with others, generate a PDF, and more.

Site Scan

This scan checks for common coding practices that may cause user experience problems. It will also suggest fixes when it can. Not only that, but the source is available on GitHub so that you can run scans independently of modern.IE and the Cloud.

Site Scan

I ran this against my blog and it took just over seven seconds to return the results.

Compatibility Report

Compatibility Scan

This feature will scan a given site for patterns of interactions that are known to cause issues in web browsers.  The first time I tried to run this, it did not work. However, a second attempt gave me results.

Debugging IIS Express website from a HyperV Virtual Machine

Recently, I had to investigate a performance bug on a website when using Internet Explorer 8. Although we are fortunate to have access to BrowserStack for testing, I have not found it particularly efficient for performance investigations, so instead I used an HyperV virtual machine (VM) from modern.IE.

I had started the site under test from Visual Studio 2013 using IIS Express. Unfortunately, HyperV VMs are not able to see such a site out-of-the-box. Three things must be reconfigured first: the VM network adapter, the Windows Firewall of the host machine, and IIS Express.

HyperV VM Network Adapter

HyperV Virtual Switch Manager
HyperV Virtual Switch Manager

In HyperV, select Virtual Switch Manager… from the Actions list on the right-hand side. In the dialog that appears, select New virtual network switch on the left, then Internal on the right, then click Create Virtual Switch. This creates a virtual network switch that allows your VM to see your local machine and vice versa. You can then name the switch anything you want; I called mine LocalDebugNet.

New virtual network switch
New virtual network switch

To ensure the VM uses the newly created virtual switch, select the VM and choose Settings… (either from the context menu or the lower-right pane). Choose Add Hardware in the left-hand pane and add a new Network Adapter, then drop down the virtual switch list on the right, choose the switch you created earlier, and click OK to accept the changes and close the dialog.

Add network adapter
Add network adapter
Set virtual switch on network adapter
Set virtual switch on network adapter

Now the VM is setup and should be able to see its host machine on its network. Unfortunately, it still cannot see the website under test. Next, we have to configure IIS Express.

IIS Express

Open up a command prompt on your machine (the host machine, not the VM) and run ipconfig /all . Look in the output for the virtual switch that you created earlier and write down the corresponding IP address1.

Command prompt showing ipconfig
Command prompt showing ipconfig

Open the IIS Express applicationhost.config file in your favourite text editor. This file is usually found under your user profile.

notepad %USERPROFILE%\documents\iisexpress\config\applicationhost.config

Find the website that you are testing and add a binding for the IP address you wrote down earlier and the port that the site is running on. You can usually just copy the localhost binding and change localhost to the IP address or your machine name.

You will also need to run this command as an administrator to add an http access rule, where <ipaddress>  should be replaced with the IP you wrote down or your machine name, and <port>  should be replaced with the port on which IIS Express hosts your website.

netsh http add urlacl url=http://<ipaddress>:<port>/ user=everyone

At this point, you might be in luck. Try restarting IIS Express and navigating to your site from inside the HyperV VM. If it works, you are all set; if not, you will need to add a rule to the Windows Firewall (or whatever firewall software you have running).

Windows Firewall

The VM can see your machine and IIS Express is binding to the appropriate IP address and port, but the firewall is preventing traffic on that port. To fix this, we can add an inbound firewall rule. To do this, open up Windows Firewall from Control Panel and click Advanced Settings or search Windows for Windows Firewall with Advanced Security and launch that.

Inbound rules in Windows Firewall
Inbound rules in Windows Firewall

Select Inbound Rules on the left, then New Rule… on the right and set up a new rule to allow connections the port where your site is hosted by IIS Express. I have shown an example here in the following screen grabs, but use your own discretion and make sure not to give too much access to your machine.

New inbound port rule
New inbound port rule
Specifying rule port
Specifying rule port
Setting rule to allow the connection
Setting rule to allow the connection
Inbound rule application
Inbound rule application
Naming the rule
Naming the rule

Once you have set up a rule to allow access via the appropriate port, you should be able to see your IIS Express hosted site from inside your VM of choice.

As always, if you have any feedback, please leave a comment.

  1. You can also try using the name of your machine for the following steps instead of the IP []

Testing AngularJS: $resource

This is the fourth post taking a look at testing various aspects of AngularJS. Previously, I covered:

In this installment we'll take a look at what I do to isolate components from their use of the $resource service and why.

$resource

The $resource service provides a simple way to define RESTful API endpoints in AngularJS and get updated data without lots of promise handling unnecessarily obfuscating your code. If you have created a resource for a specific route, you can get the returned data into your scope as easily as this:

$scope.data = myResource.get();

The $resource magic ensures that once the request returns, the data is updated. It's clever stuff and incredibly useful.

However, when testing components that use resources, I want to isolate the components from those resources. While I could use $httpBackend or a cache to manipulate what results the resource returns, these can be cumbersome to setup and adds unnecessary complexity and churn to unit tests1. To avoid this complexity, I use a fake that can be substituted for $resource.

spyResource

My fake $resource is called spyResource. It is not quite a 1-1 replacement, but it does support the more common situations one might want (and it could be extended to support more). Here it is.

spyResource = function (name) {
	var resourceSpy = jasmine.createSpy(name + ' resource constructor').and.callFake(function () { angular.copy({}, this); });

	resourceSpy['get'] = resourceSpy.prototype['get'] = jasmine.createSpy('get');
	resourceSpy['$save'] = resourceSpy.prototype['$save'] = jasmine.createSpy('$save');
	resourceSpy['$delete'] = resourceSpy.prototype['$delete'] = jasmine.createSpy('$delete');

	return resourceSpy;
};

First of all, it is just a function. Since it is part of my testing framework, there is no need to wrap it in some fancy AngularJS factory, though we certainly could if we wanted.

Second, it mimics the $resource service by returning a function that ultimately copies itself. This is useful because you do not necessarily have access to the instances of a resource that are created in your code before posting an object update to your RESTful API. By copying itself, you can see if the $save() call is made directly from the main spyResource definition, even if it was actually called on an instance returned by it because they share the same spies.

To use this in testing, the $provide service can be used to replace a specific use of $resource with a spyResource. For example, if you defined a resource called someResource, you might have:

describe 'testing something that uses a resource', ->
  Given => module ($provide) =>
    $provide.value 'someResource', spyResource('someResource');return
  ...

Now, the fake resource will be injected instead of the real one, allowing us to not only spy on it, but to also ensure there are no side-effects that we have not explicitly set up.

Finally…

I have covered a very simple technique I use for isolating components from and spying on their usage of AngularJS resources. The simple fake resource I provided for this purpose can be easily tailored to cater to more complex scenarios. For example, if the code under test needs data from the get() method or the $promise property is expected in get() return result, the spy can be updated to return that data.

Using this fake resource instead of $httpBackend or a cache to manipulate the behavior of a real AngularJS resource not only simplifies the testing in general, but also reduces code churn by isolating the tests from the API routes that can often change during development.

As always, please leave a comment if you find this useful or have other feedback.

 

 

  1. API routes can often change during development, which would lead to updating `$httpBackend` test code so that it matches []

Testing AngularJS: Asynchrony

So far, we have looked at some techniques for testing simple AngularJS factories and directives. However, things are rarely simple when it comes to web development and one area that complicates things is that of asynchronous operations such as web requests, timeouts and promises.

Eventually, when writing AngularJS, you will rely on the $timeout, $interval, or $q services to defer an action by some interval or indefinitely using promises. I will not go very deep into their use here, you can read much of that on the AngularJS documentation, but since it is likely that you will use them, how do you test them? How do you test asynchronous code without horribly complex and unreliable tests?

$timeout

Consider this simple example where we have a controller that defers some action using $timeout.

somewhatAbstract.controller('DeferredController', ['$scope', '$timeout', function ($scope, $timeout) {
    $scope.started = false;

    $timeout(function() {
        $scope.started = true;
    } );
}

Here we have a variable, started that is initialised to false and a deferred method that changes that value to true. A first stab at testing this might look a little like this:

describe 'deferred execution tests', ->
  describe 'started should be set to true', ->
    Given => module 'somewhatAbstract'
    Given => inject ($rootScope) =>
      @scope = $rootScope.$new()
    When => inject ($timeout, $controller) =>
      $controller 'deferredController', { $scope: @scope, $timeout: $timeout }
    Then => expect(@scope.started).toBeTruthy()

Unfortunately, such a test will not pass because the deferred code would not execute until after the expectation was tested. We can mitigate this by using some AngularJS magic provided by the ngMock module.

The ngMock module adds the $timeout.flush() method so that code deferred using $timeout can be executed deterministically1. The test can therefore be modified such that it passes by adding the highlighted line below.

describe 'deferred execution tests', ->
  describe 'started should be set to true', ->
    Given => module 'somewhatAbstract'
    Given => inject ($rootScope) =>
      @scope = $rootScope.$new()
    When => inject ($timeout, $controller) =>
      $controller 'deferredController', { $scope: @scope, $timeout: $timeout }
      $timeout.flush()
    Then => expect(@scope.started).toBeTruthy()

$q

For promises that were deferred using $q (including the promise returned from using $interval), we can use $scope.$apply() to complete a resolved or rejected promise and execute any code depending on that promise.

In the following contrived example, we have a controller with a start() method that returns a promise and a started() method that resolves that promise.

somewhatAbstract.controller('deferredController', ['$scope', '$timeout', '$q', function ($scope, $timeout, $q) {
    var deferred = $q.defer();

    $scope.start = function () {
        return deferred.promise;
    };

    $scope.started = function() {
        deferred.resolve({started:true}); };
    };
}]);
describe 'deferred execution tests', ->
  describe 'started should be set to true when promise resolves', ->
    Given => module 'somewhatAbstract'
    Given => inject ($rootScope, $q, $controller) =>
      @scope = $rootScope.$new()
      $controller 'deferredController', { $scope: @scope, $q: $q }
    When =>
      @scope.start().then (result) => @actual = result
      @scope.started()
      @scope.$apply()
    Then => expect(@result).toBe { started: true }

The preceding test validates our controller and its promise. If you delete the highlighted line, you would see that the test fails because the resolved promise is never completed.

Finally…

In this post, we have taken a brief look at how AngularJS supports the testing of asynchronous code execution deferred using $timeout, $interval, or $q. The ability to synchronously control otherwise asynchronous actions not only allows us to test that deferred code, but also to prevent it executing at all. This can be incredibly useful when isolating different parts of our code by reducing how much of it has to run to validate a specific method.

Of course, quite often, a promise is only resolved after an HTTP request responds or fails, such as when using $resource. When writing unit tests, you may not have nor want the luxury of a back-end server that responds appropriately to test requests. Instead, you either want to fake out $resource, or fake out and validate the HTTP requests and responses2. In upcoming posts, we'll look at a simple $resource fake for the former and the special $httpBackend service that AngularJS provides for the latter. Until then, please leave your comments.

  1. The `flush()` method even takes a delay parameter to control which timeouts will execute and a similar method exists for `$interval` []
  2. The requests that you expect your code to make and the responses that your code expects to receive – or doesn't, as the case may be []