Add success test case for mission launch

test/MissionControl.Server.Tests/Endpoints/Missions/MissionLaunches/CreateMissionLaunchTests.cs

@@ -44,4 +44,44 @@ public class CreateMissionLaunchTests
             e.PropertyName == nameof(CreateMissionLaunchRequest.MissionId)
         );
     }
+
+    [Fact]
+    public async Task Creates_mission_launch_when_request_is_valid_and_mission_exists()
+    {
+        var utcNow = DateTimeOffset.UtcNow;
+
+        using var database = new TestDatabase();
+        var mission = await createMission(database);
+
+        var endpoint = Factory.Create<CreateMissionLaunch>(database.Context);
+        var request = new CreateMissionLaunchRequest
+        {
+            MissionId = mission.Id,
+            ScheduledFor = utcNow,
+            Status = MissionLaunchStatus.Cancelled,
+        };
+
+        await endpoint.HandleAsync(request, CancellationToken.None);
+
+        var response = endpoint.Response;
+
+        endpoint.HttpContext.Response.StatusCode.ShouldBe(StatusCodes.Status200OK);
+        response.Id.ShouldNotBe(Guid.Empty);
+        response.ScheduledFor.ShouldBe(utcNow);
+        response.Status.ShouldBe(MissionLaunchStatus.Cancelled);
+    }
+
+    private static async Task<Mission> createMission(TestDatabase database)
+    {
+        var mission = new Mission
+        {
+            Name = "new mission",
+            Description = "mission description",
+        };
+
+        database.Context.Missions.Add(mission);
+        await database.Context.SaveChangesAsync();
+
+        return mission;
+    }
 }