Test driven development and Mock service

Scenario:

Write a test to verify if the user can be successfully created.

Solution:

• Create MockService as below

public interface IRepoRes
{   
    IDataRepository<T> GetDataRepository<T>(DataCommand command);
}

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public class MockRepo : IRepoRes
{
    private readonly Dictionary<string, Option<object>> _info;

    public MockRepo(IRepoRes real)
    {
        _info = new Dictionary<string, Option<object>>(StringComparer.InvariantCultureIgnoreCase);
    }
    public IDataRepo<T> GetDataRepo<T>(Command command)
    {
        MockRepo<T> loadedInfo;
        return TryLoadInfo(command, commandKey, out loadedInfo)
            ? Option.Some((object)loadedInfo)
            : Option.None<object>();
    }

    private  TryLoadInfo<T>(DataCommand command, string key, out MockRepo<T> info)
    {
        try
        {
            var st = new StackTrace();

            var testClass =
                st.GetFrames()
                    .Select(f => f.GetMethod())
                    .Where(m => m.GetCustomAttributes(typeof(FactAttribute), false).Length > 0)
                    .Select(m => m.DeclaringType)

            var path = new[]
            {
                string.Format("Environment.CurrentDirectory/App_info/DataCommands/command.CommandKey/testClass == null ? "" : string.Format("{0}_", testClass.Name)key.json"),
                string.Format("Environment.CurrentDirectory/App_info/DataCommands/command.CommandKey/key.json")
            }.FirstOrDefault(File.Exists);

            var serializer = new DataContractJsonSerializer(typeof(T[]));

                var d = new List<T>();
                using (var inputStream = new FileStream(path, FileMode.Open))
                {
                    using (var ms = new MemoryStream())
                    {
                        //load into MemoryStream

                        if (typeof(T) == typeof(ExpandoObject))
                        {
                            var objs = JsonConvert.DeserializeObject<IEnumerable<JObject>>(Encoding.Default.GetString(ms.ToArray()));

                            foreach (var obj in objs)
                            {
                                dynamic dynObj = new ExpandoObject();
                                var dynDict = dynObj as IDictionary<string, object>;
                                foreach (var property in obj.Properties())
                                {
                                    dynDict[property.Name] = obj.GetValue(property.Name);
                                }
                                d.Add((T)dynObj);
                            }
                        }
                        else
                        {
                            d.AddRange((T[])serializer.ReadObject(ms));
                        }

                    }
                }

                info = new MockRepo<T>();
                info.AddData(key, d);
        }
    }
}


public class MockRepo<T> : IDataRepo<T>
{
    private readonly Dictionary<string, IEnumerable<T>> _info;
       
    public void AddData(string key, IEnumerable<T> info)
    {
        _info[key] = info;
    }

    public IEnumerable<T> ExecuteQuery(Command command)
    {
        IEnumerable<T> infos;

        var key = string.Join("_", command.CommandParameters.OrderBy(p => p.Name, StringComparer.InvariantCultureIgnoreCase).Select(p => string.Format("{0}={1}", p.Name, p.Value == null ? "" : p.Value.ToString())))
                        : "__d__";
        return infos;
    }
}

• Create Test case

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using Xunit;

[Fact]
public void TestGetUsers()
{
    var users = LoadDataFile("TestUsers\\Users.json",
        s => _searalizer.ReadObject(s) as User[]);

    Assert.True(userService.TryGetUsers(users, out var userInfos));
    Assert.NotNull(userInfos);
    Assert.Equal(1, userInfos[1].Id);
    Assert.Equal("Test", userInfos[1].Name);
}

• Users.json as below

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{
  "Id": 1,
  "Name": "Test"
}

• GetUsersCommand [UserId=1.json]

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[
    {
        "UserId": 1,
        "Name": "Test"
    }
]