test(udt-001): backend unit and integration tests (30 tests)

tests/SIGCM2.Application.Tests/Auth/Login/LoginCommandValidatorTests.cs

@@ -0,0 +1,55 @@
+using FluentValidation.TestHelper;
+using SIGCM2.Application.Auth.Login;
+
+namespace SIGCM2.Application.Tests.Auth.Login;
+
+public class LoginCommandValidatorTests
+{
+    private readonly LoginCommandValidator _validator = new();
+
+    // Happy path: valid command passes validation
+    [Fact]
+    public void Validate_ValidCommand_ShouldHaveNoErrors()
+    {
+        var command = new LoginCommand("admin", "@Diego550@");
+        var result = _validator.TestValidate(command);
+        result.ShouldNotHaveAnyValidationErrors();
+    }
+
+    // Scenario: empty username → validation error referencing Username
+    [Fact]
+    public void Validate_EmptyUsername_ShouldHaveErrorForUsername()
+    {
+        var command = new LoginCommand("", "@Diego550@");
+        var result = _validator.TestValidate(command);
+        result.ShouldHaveValidationErrorFor(c => c.Username);
+    }
+
+    // Triangulation: whitespace-only username
+    [Fact]
+    public void Validate_WhitespaceUsername_ShouldHaveErrorForUsername()
+    {
+        var command = new LoginCommand("   ", "@Diego550@");
+        var result = _validator.TestValidate(command);
+        result.ShouldHaveValidationErrorFor(c => c.Username);
+    }
+
+    // Scenario: missing password → validation error referencing Password
+    [Fact]
+    public void Validate_EmptyPassword_ShouldHaveErrorForPassword()
+    {
+        var command = new LoginCommand("admin", "");
+        var result = _validator.TestValidate(command);
+        result.ShouldHaveValidationErrorFor(c => c.Password);
+    }
+
+    // Triangulation: null-equivalent (empty string is how records serialize missing fields)
+    [Fact]
+    public void Validate_BothEmpty_ShouldHaveErrorsForBothFields()
+    {
+        var command = new LoginCommand("", "");
+        var result = _validator.TestValidate(command);
+        result.ShouldHaveValidationErrorFor(c => c.Username);
+        result.ShouldHaveValidationErrorFor(c => c.Password);
+    }
+}