feat(OTP): [PM-18612] Change email OTP to six digits

* Change email OTP to 6 digits

* Added comment on base class

* Added tests

* Renamed tests.

* Fixed tests

* Renamed file to match class

test/Core.Test/Auth/Identity/AuthenticationTwoFactorTokenProviderTests.cs

@@ -7,7 +7,7 @@ using Xunit;
 
 namespace Bit.Core.Test.Auth.Identity;
 
-public class AuthenticationTokenProviderTests : BaseTokenProviderTests<AuthenticatorTokenProvider>
+public class AuthenticationTwoFactorTokenProviderTests : BaseTwoFactorTokenProviderTests<AuthenticatorTokenProvider>
 {
     public override TwoFactorProviderType TwoFactorProviderType => TwoFactorProviderType.Authenticator;
 

test/Core.Test/Auth/Identity/BaseTwoFactorTokenProviderTests.cs

@@ -14,7 +14,7 @@ using Xunit;
 namespace Bit.Core.Test.Auth.Identity;
 
 [SutProviderCustomize]
-public abstract class BaseTokenProviderTests<T>
+public abstract class BaseTwoFactorTokenProviderTests<T>
     where T : IUserTwoFactorTokenProvider<User>
 {
     public abstract TwoFactorProviderType TwoFactorProviderType { get; }

test/Core.Test/Auth/Identity/DuoUniversalTwoFactorTokenProviderTests.cs

@@ -12,7 +12,7 @@ using Duo = DuoUniversal;
 
 namespace Bit.Core.Test.Auth.Identity;
 
-public class DuoUniversalTwoFactorTokenProviderTests : BaseTokenProviderTests<DuoUniversalTokenProvider>
+public class DuoUniversalTwoFactorTokenProviderTests : BaseTwoFactorTokenProviderTests<DuoUniversalTokenProvider>
 {
     private readonly IDuoUniversalTokenService _duoUniversalTokenService = Substitute.For<IDuoUniversalTokenService>();
     public override TwoFactorProviderType TwoFactorProviderType => TwoFactorProviderType.Duo;

test/Core.Test/Auth/Identity/EmailTokenProviderTests.cs

@@ -0,0 +1,68 @@
+using Bit.Core;
+using Bit.Core.Auth.Identity.TokenProviders;
+using Bit.Core.Entities;
+using Bit.Core.Services;
+using Bit.Test.Common.AutoFixture.Attributes;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.Extensions.Caching.Distributed;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using NSubstitute;
+using Xunit;
+
+[SutProviderCustomize]
+public class EmailTokenProviderTests
+{
+    private readonly IDistributedCache _cache;
+
+    public EmailTokenProviderTests()
+    {
+        _cache = Substitute.For<IDistributedCache>();
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task GenerateAsync_GeneratesSixDigitToken_WhenFeatureFlagIsEnabled(User user)
+    {
+        // Arrange
+        var purpose = "test-purpose";
+        var featureService = Substitute.For<IFeatureService>();
+        featureService.IsEnabled(FeatureFlagKeys.Otp6Digits).Returns(true);
+        var tokenProvider = new EmailTokenProvider(_cache, featureService);
+
+        // Act
+        var code = await tokenProvider.GenerateAsync(purpose, SubstituteUserManager(), user);
+
+        // Assert
+        Assert.Equal(6, code.Length);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task GenerateAsync_GeneratesEightDigitToken_WhenFeatureFlagIsDisabled(User user)
+    {
+        // Arrange
+        var purpose = "test-purpose";
+        var featureService = Substitute.For<IFeatureService>();
+        featureService.IsEnabled(FeatureFlagKeys.Otp6Digits).Returns(false);
+        var tokenProvider = new EmailTokenProvider(_cache, featureService);
+        // Act
+        var code = await tokenProvider.GenerateAsync(purpose, SubstituteUserManager(), user);
+
+        // Assert
+        Assert.Equal(8, code.Length);
+    }
+
+    protected static UserManager<User> SubstituteUserManager()
+    {
+        return new UserManager<User>(Substitute.For<IUserStore<User>>(),
+            Substitute.For<IOptions<IdentityOptions>>(),
+            Substitute.For<IPasswordHasher<User>>(),
+            Enumerable.Empty<IUserValidator<User>>(),
+            Enumerable.Empty<IPasswordValidator<User>>(),
+            Substitute.For<ILookupNormalizer>(),
+            Substitute.For<IdentityErrorDescriber>(),
+            Substitute.For<IServiceProvider>(),
+            Substitute.For<ILogger<UserManager<User>>>());
+    }
+}

test/Core.Test/Auth/Identity/EmailTwoFactorTokenProviderTests.cs

@@ -1,13 +1,15 @@
 using Bit.Core.Auth.Enums;
 using Bit.Core.Auth.Identity.TokenProviders;
 using Bit.Core.Entities;
+using Bit.Core.Services;
 using Bit.Test.Common.AutoFixture;
 using Bit.Test.Common.AutoFixture.Attributes;
+using NSubstitute;
 using Xunit;
 
 namespace Bit.Core.Test.Auth.Identity;
 
-public class EmailTwoFactorTokenProviderTests : BaseTokenProviderTests<EmailTwoFactorTokenProvider>
+public class EmailTwoFactorTokenProviderTests : BaseTwoFactorTokenProviderTests<EmailTwoFactorTokenProvider>
 {
     public override TwoFactorProviderType TwoFactorProviderType => TwoFactorProviderType.Email;
 
@@ -42,4 +44,48 @@ public class EmailTwoFactorTokenProviderTests : BaseTokenProviderTests<EmailTwoF
     {
         await base.RunCanGenerateTwoFactorTokenAsync(metaData, expectedResponse, user, sutProvider);
     }
+
+    [Theory]
+    [BitAutoData]
+    public async Task GenerateAsync_ShouldReturnSixDigitToken_WithFeatureFlagEnabled(
+        User user, SutProvider<EmailTwoFactorTokenProvider> sutProvider)
+    {
+        // Arrange
+        user.TwoFactorProviders = GetTwoFactorEmailProvidersJson();
+        sutProvider.GetDependency<IFeatureService>()
+            .IsEnabled(FeatureFlagKeys.Otp6Digits)
+            .Returns(true);
+
+        // Act
+        var token = await sutProvider.Sut.GenerateAsync("purpose", SubstituteUserManager(), user);
+
+        // Assert
+        Assert.NotNull(token);
+        Assert.Equal(6, token.Length);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task GenerateAsync_ShouldReturnSixDigitToken_WithFeatureFlagDisabled(
+        User user, SutProvider<EmailTwoFactorTokenProvider> sutProvider)
+    {
+        // Arrange
+        user.TwoFactorProviders = GetTwoFactorEmailProvidersJson();
+        sutProvider.GetDependency<IFeatureService>()
+            .IsEnabled(FeatureFlagKeys.Otp6Digits)
+            .Returns(false);
+
+        // Act
+        var token = await sutProvider.Sut.GenerateAsync("purpose", SubstituteUserManager(), user);
+
+        // Assert
+        Assert.NotNull(token);
+        Assert.Equal(6, token.Length);
+    }
+
+    private string GetTwoFactorEmailProvidersJson()
+    {
+        return
+            "{\"1\":{\"Enabled\":true,\"MetaData\":{\"Email\":\"test@email.com\"}}}";
+    }
 }