Add new AddGrantTypePermissions()/RemoveGrantTypePermissions() APIs in OpenIddictApplicationDescriptor

src/OpenIddict.Abstractions/Descriptors/OpenIddictApplicationDescriptor.cs

@@ -102,6 +102,27 @@ public OpenIddictApplicationDescriptor AddAudiencePermissions(params string[] au
         return this;
     }
 
+    /// <summary>
+    /// Adds grant type permissions for all the specified <paramref name="types"/>.
+    /// </summary>
+    /// <param name="types">The grant types for which grant types permissions will be added.</param>
+    /// <returns>The <see cref="OpenIddictApplicationDescriptor"/> instance.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="types"/> is <see langword="null"/>.</exception>
+    public OpenIddictApplicationDescriptor AddGrantTypePermissions(params string[] types)
+    {
+        if (types is null)
+        {
+            throw new ArgumentNullException(nameof(types));
+        }
+
+        foreach (var type in types)
+        {
+            Permissions.Add(OpenIddictConstants.Permissions.Prefixes.GrantType + type);
+        }
+
+        return this;
+    }
+
     /// <summary>
     /// Adds resource permissions for all the specified <paramref name="resources"/>.
     /// </summary>
@@ -333,6 +354,27 @@ public OpenIddictApplicationDescriptor RemoveAudiencePermissions(params string[]
         return this;
     }
 
+    /// <summary>
+    /// Removes all the grant type permissions corresponding to the specified <paramref name="types"/>.
+    /// </summary>
+    /// <param name="types">The grant types for which grant types permissions will be removed.</param>
+    /// <returns>The <see cref="OpenIddictApplicationDescriptor"/> instance.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="types"/> is <see langword="null"/>.</exception>
+    public OpenIddictApplicationDescriptor RemoveGrantTypePermissions(params string[] types)
+    {
+        if (types is null)
+        {
+            throw new ArgumentNullException(nameof(types));
+        }
+
+        foreach (var type in types)
+        {
+            Permissions.Remove(OpenIddictConstants.Permissions.Prefixes.GrantType + type);
+        }
+
+        return this;
+    }
+
     /// <summary>
     /// Removes all the resource permissions corresponding to the specified <paramref name="resources"/>.
     /// </summary>

test/OpenIddict.Abstractions.Tests/Descriptors/OpenIddictApplicationDescriptorTests.cs

@@ -29,6 +29,30 @@ public void AddAudiencePermissions_ThrowsAnExceptionForNullAudiences()
         Assert.Throws<ArgumentNullException>(() => descriptor.AddAudiencePermissions(null!));
     }
 
+    [Fact]
+    public void AddGrantTypePermissions_AddsPermissions()
+    {
+        // Arrange
+        var descriptor = new OpenIddictApplicationDescriptor();
+
+        // Act
+        descriptor.AddGrantTypePermissions(GrantTypes.Implicit, "custom_grant_type");
+
+        // Assert
+        Assert.Contains(OpenIddictConstants.Permissions.Prefixes.GrantType + GrantTypes.Implicit, descriptor.Permissions);
+        Assert.Contains(OpenIddictConstants.Permissions.Prefixes.GrantType + "custom_grant_type", descriptor.Permissions);
+    }
+
+    [Fact]
+    public void AddGrantTypePermissions_ThrowsAnExceptionForNullGrantTypes()
+    {
+        // Arrange
+        var descriptor = new OpenIddictApplicationDescriptor();
+
+        // Act and assert
+        Assert.Throws<ArgumentNullException>(() => descriptor.AddGrantTypePermissions(null!));
+    }
+
     [Fact]
     public void AddResourcePermissions_AddsPermissions()
     {
@@ -270,6 +294,31 @@ public void RemoveAudiencePermissions_ThrowsAnExceptionForNullAudiences()
         Assert.Throws<ArgumentNullException>(() => descriptor.RemoveAudiencePermissions(null!));
     }
 
+    [Fact]
+    public void RemoveGrantTypePermissions_RemovesPermissions()
+    {
+        // Arrange
+        var descriptor = new OpenIddictApplicationDescriptor();
+        descriptor.AddGrantTypePermissions(GrantTypes.Implicit, "custom_grant_type");
+
+        // Act
+        descriptor.RemoveGrantTypePermissions(GrantTypes.Implicit);
+
+        // Assert
+        Assert.DoesNotContain(GrantTypes.Implicit, descriptor.Permissions);
+        Assert.Contains(OpenIddictConstants.Permissions.Prefixes.GrantType + "custom_grant_type", descriptor.Permissions);
+    }
+
+    [Fact]
+    public void RemoveGrantTypePermissions_ThrowsAnExceptionForNullGrantTypes()
+    {
+        // Arrange
+        var descriptor = new OpenIddictApplicationDescriptor();
+
+        // Act and assert
+        Assert.Throws<ArgumentNullException>(() => descriptor.RemoveGrantTypePermissions(null!));
+    }
+
     [Fact]
     public void RemoveResourcePermissions_RemovesPermissions()
     {