public async Task AllPosts()
{
var options = new DbContextOptionsBuilder <ApplicationDbContext>()
.UseInMemoryDatabase(databaseName: "AllPosts_Database")
.Options;
var dbContext = new ApplicationDbContext(options);
var postService = new PostService(dbContext);
await postService.CreatePostAsync("Tweets", "Hello i am tweet", "u1", 1);
await postService.CreatePostAsync("Tweets2", "Hello i am tweet2", "u1", 1);
var allPosts = postService.AllPosts(null, null);
var firstPost = await allPosts.FirstAsync();
Assert.Equal("Tweets", firstPost.Title);
Assert.Equal("Hello i am tweet", firstPost.Content);
Assert.Equal("u1", firstPost.UserId);
Assert.Equal(2, await allPosts.CountAsync());
}