Refactor KeycloakRealmResource and enhance validation

The `KeycloakRealmResource` class has been refactored to include null checks in its constructor for parameters `name`, `realmName`, and `parent`. A private field `_parentEndpoint` and a property `ParentEndpoint` have been added. The `Parent` and `RealmName` properties now rely on the constructor for initialization.

New unit tests in `KeycloakPublicApiTests.cs` ensure that the constructor throws an `ArgumentNullException` for null parameters. Additional tests validate that the `AddRealm` method correctly handles null values for the builder and realm name, improving input validation across the API.

src/Aspire.Hosting.Keycloak/KeycloakRealmResource.cs

@@ -8,12 +8,25 @@ namespace Aspire.Hosting.Keycloak;
 /// <summary>
 /// Represents a Keycloak Realm resource.
 /// </summary>
-/// <param name="name">The name of the realm resource.</param>
-/// <param name="realmName">The name of the realm.</param>
-/// <param name="parent">The Keycloak server resource associated with this database.</param>
-public sealed class KeycloakRealmResource(string name, string realmName, KeycloakResource parent) : Resource(name), IResourceWithParent<KeycloakResource>, IResourceWithConnectionString
+public sealed class KeycloakRealmResource : Resource, IResourceWithParent<KeycloakResource>, IResourceWithConnectionString
 {
     private EndpointReference? _parentEndpoint;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="KeycloakRealmResource"/> class.
+    /// </summary>
+    /// <param name="name">The name of the realm resource.</param>
+    /// <param name="realmName">The name of the realm.</param>
+    /// <param name="parent">The Keycloak server resource associated with this database.</param>
+    public KeycloakRealmResource(string name, string realmName, KeycloakResource parent) : base(name)
+    {
+        ArgumentNullException.ThrowIfNull(realmName);
+        ArgumentNullException.ThrowIfNull(parent);
+
+        RealmName = realmName;
+        Parent = parent;
+    }
+
     private EndpointReference ParentEndpoint => _parentEndpoint ??= new(Parent, "http");
 
     /// <inheritdoc/>
@@ -96,10 +109,10 @@ public sealed class KeycloakRealmResource(string name, string realmName, Keycloa
     public ReferenceExpression RegistrationEndpointExpression => ReferenceExpression.Create($"{ConnectionStringExpression}{RegistrationEndpoint}");
 
     /// <inheritdoc/>
-    public KeycloakResource Parent { get; } = parent;
+    public KeycloakResource Parent { get; }
 
     /// <summary>
     /// Gets the name of the realm.
     /// </summary>
-    public string RealmName { get; } = realmName;
+    public string RealmName { get; }
 }

tests/Aspire.Hosting.Keycloak.Tests/KeycloakPublicApiTests.cs

@@ -34,6 +34,49 @@ public void CtorKeycloakResourceShouldThrowWhenAdminPasswordIsNull()
         Assert.Equal(nameof(adminPassword), exception.ParamName);
     }
 
+    [Fact]
+    public void CtorKeycloakRealmResourceShouldThrowWhenNameIsNull()
+    {
+        string name = null!;
+        var realmName = "realm1";
+        var builder = TestDistributedApplicationBuilder.Create();
+        var adminPassword = builder.AddParameter("Password");
+        var parent = new KeycloakResource("keycloak", default(ParameterResource?), adminPassword.Resource);
+
+        var action = () => new KeycloakRealmResource(name, realmName, parent);
+
+        var exception = Assert.Throws<ArgumentNullException>(action);
+        Assert.Equal(nameof(name), exception.ParamName);
+    }
+
+    [Fact]
+    public void CtorMongoKeycloakRealmResourceShouldThrowWhenRealmNameIsNull()
+    {
+        var name = "keycloak";
+        string realmName = null!;
+        var builder = TestDistributedApplicationBuilder.Create();
+        var adminPassword = builder.AddParameter("Password");
+        var parent = new KeycloakResource("keycloak", default(ParameterResource?), adminPassword.Resource);
+
+        var action = () => new KeycloakRealmResource(name, realmName, parent);
+
+        var exception = Assert.Throws<ArgumentNullException>(action);
+        Assert.Equal(nameof(realmName), exception.ParamName);
+    }
+
+    [Fact]
+    public void CtorMongoKeycloakRealmResourceShouldThrowWhenDatabaseParentIsNull()
+    {
+        var name = "keycloak";
+        var realmName = "realm1";
+        KeycloakResource parent = null!;
+
+        var action = () => new KeycloakRealmResource(name, realmName, parent);
+
+        var exception = Assert.Throws<ArgumentNullException>(action);
+        Assert.Equal(nameof(parent), exception.ParamName);
+    }
+
     [Fact]
     public void AddKeycloakContainerShouldThrowWhenBuilderIsNull()
     {
@@ -129,4 +172,29 @@ public void WithRealmImportShouldThrowWhenImportDirectoryDoesNotExist()
 
         Assert.Throws<DirectoryNotFoundException>(action);
     }
+
+    [Fact]
+    public void AddRealmShouldThrowWhenBuilderIsNull()
+    {
+        IResourceBuilder<KeycloakResource> builder = null!;
+        const string name = "realm1";
+
+        var action = () => builder.AddRealm(name);
+
+        var exception = Assert.Throws<ArgumentNullException>(action);
+        Assert.Equal(nameof(builder), exception.ParamName);
+    }
+
+    [Fact]
+    public void AddRealmShouldThrowWhenNameIsNull()
+    {
+        var builderResource = TestDistributedApplicationBuilder.Create();
+        var MongoDB = builderResource.AddKeycloak("realm1");
+        string name = null!;
+
+        var action = () => MongoDB.AddRealm(name);
+
+        var exception = Assert.Throws<ArgumentNullException>(action);
+        Assert.Equal(nameof(name), exception.ParamName);
+    }
 }