Add tests

BudgetApp.Tests/Helpers/TestDbContextFactory.cs

@@ -0,0 +1,51 @@
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using BudgetApp.Data;
+
+namespace BudgetApp.Tests.Helpers;
+
+public sealed class TestDbContextFactory : IDisposable
+{
+    private readonly SqliteConnection _connection;
+
+    public const string TestUserId = "test-user-id";
+    public const string OtherUserId = "other-user-id";
+
+    public TestDbContextFactory()
+    {
+        _connection = new SqliteConnection("DataSource=:memory:");
+        _connection.Open();
+
+        using var context = CreateContext();
+        context.Database.EnsureCreated();
+
+        context.Users.AddRange(
+            new ApplicationUser
+            {
+                Id = TestUserId,
+                UserName = "test@test.com",
+                NormalizedUserName = "TEST@TEST.COM",
+                Email = "test@test.com",
+                NormalizedEmail = "TEST@TEST.COM"
+            },
+            new ApplicationUser
+            {
+                Id = OtherUserId,
+                UserName = "other@test.com",
+                NormalizedUserName = "OTHER@TEST.COM",
+                Email = "other@test.com",
+                NormalizedEmail = "OTHER@TEST.COM"
+            });
+        context.SaveChanges();
+    }
+
+    public ApplicationDbContext CreateContext()
+    {
+        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
+            .UseSqlite(_connection)
+            .Options;
+        return new ApplicationDbContext(options);
+    }
+
+    public void Dispose() => _connection.Dispose();
+}