Add unit tests for the server controller (#16)

## What does this PR do ?
Add unit test for server controller. 

### Other changes
Fix the query made in `getStatsAsync` function : action was `getLastStats` while [it should be](https://docs.kuzzle.io/core/1/api/controllers/server/get-stats/) `getStats`

Author: Thomas Falcone

Kuzzle.Tests/API/Controllers/ServerControllerTest.cs

@@ -0,0 +1,137 @@
+using Xunit;
+using KuzzleSdk.API.Controllers;
+using Newtonsoft.Json.Linq;
+using System;
+
+namespace Kuzzle.Tests.API.Controllers
+{
+    public class ServerControllerTest
+    {
+        private readonly ServerController _serverController;
+        private readonly KuzzleApiMock _api;
+
+        public ServerControllerTest()
+        {
+            _api = new KuzzleApiMock();
+            _serverController = new ServerController(_api.MockedObject);
+        }
+
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public async void AdminExistsTest(bool returnValue)
+        {
+            _api.SetResult(new JObject { {
+                "result",  new JObject {
+                    { "exists", returnValue }
+                } }
+            });
+
+            bool res = await _serverController.AdminExistsAsync();
+
+            _api.Verify(new JObject{
+                { "controller", "server" },
+                { "action", "adminExists"}
+            });
+
+            Assert.Equal(returnValue, res);
+        }
+
+
+        [Fact]
+        public async void NowTest()
+        {
+            _api.SetResult(@"{result: {now: 1111111111111}}");
+
+            Int64 res = await _serverController.NowAsync();
+
+            _api.Verify(new JObject{
+                {"controller", "server"},
+                {"action", "now"}
+            });
+            Assert.Equal<Int64>(1111111111111, res);
+        }
+    
+        [Fact]
+        public async void InfoTest(){
+            JObject serverInfo = new JObject {{ "kuzzle", "installed"}};
+            _api.SetResult(new JObject {{ "result", new JObject {{ "serverInfo", serverInfo }} }});
+
+            JObject res = await _serverController.InfoAsync();
+
+            _api.Verify(new JObject{ 
+                {"controller", "server"}, 
+                {"action", "info"}
+            });
+            Assert.Equal<JObject>(serverInfo, res);
+        }
+
+        [Fact]
+        public async void ConfigTest(){
+            _api.SetResult(@"{result: {limits: 'none'}}");
+
+            JObject res = await _serverController.GetConfigAsync();
+
+            _api.Verify(new JObject{ 
+                {"controller", "server"}, 
+                {"action", "getConfig"}
+            });
+            Assert.Equal<JObject>(
+                new JObject {{ "limits", "none"}},
+                res
+            );
+        }
+
+        [Fact]
+        public async void GetStatsTest(){
+            _api.SetResult(@"{ result: { cake: 'lie'} }");
+            long start = 0; 
+            long end = 1;
+
+            JObject res = await _serverController.GetStatsAsync(start, end);
+
+            _api.Verify(new JObject {
+                { "controller", "server" }, 
+                { "action", "getStats" },
+                { "startTime", start },
+                { "stopTime", end }
+            }); 
+            Assert.Equal<JObject>(
+                new JObject {{ "cake", "lie" }}, 
+                res
+            );
+        }
+
+        [Fact]
+        public async void GetAllStatsTest(){
+            _api.SetResult(@"{ result: { cake: 'lie'} }");
+
+            JObject res = await _serverController.GetAllStatsAsync();
+
+            _api.Verify(new JObject {
+                { "controller", "server" }, 
+                { "action", "getAllStats" }
+            }); 
+            Assert.Equal<JObject>(
+                new JObject {{ "cake", "lie" }}, 
+                res
+            );
+        }
+
+        [Fact]
+        public async void GetLastStatsTest(){
+            _api.SetResult(@"{ result: { cake: 'lie'} }");
+
+            JObject res = await _serverController.GetLastStatsAsync();
+
+            _api.Verify(new JObject {
+                { "controller", "server" }, 
+                { "action", "getLastStats" }
+            }); 
+            Assert.Equal<JObject>(
+                new JObject {{ "cake", "lie" }}, 
+                res
+            );
+        }
+    }
+}

Kuzzle/API/Controllers/ServerController.cs

@@ -7,7 +7,7 @@ namespace KuzzleSdk.API.Controllers {
   /// Implements the "server" Kuzzle API controller
   /// </summary>
   public sealed class ServerController : BaseController {
-    internal ServerController(Kuzzle k) : base(k) { }
+    internal ServerController(IKuzzleApi api) : base(api) { }
 
     /// <summary>
     /// Returns the current server timestamp, in Epoch-millis format.
@@ -89,7 +89,7 @@ public async Task<JObject> GetLastStatsAsync() {
     public async Task<JObject> GetStatsAsync(Int64 start, Int64 end) {
       Response response = await api.QueryAsync(new JObject {
         { "controller", "server" },
-        { "action", "getLastStats" },
+        { "action", "getStats" },
         { "startTime", start},
         { "stopTime", end}
       });