Test the producer registry merge edge cases; #3073

BrighterCommand · May 8, 2024 · bf9d4a6 · bf9d4a6
1 parent 7f0584c
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diff --git a/src/Paramore.Brighter/Extensions/ProducerRegistryExtensions.cs b/src/Paramore.Brighter/Extensions/ProducerRegistryExtensions.cs
@@ -7,6 +7,12 @@ public static class ProducerRegistryExtensions
     {
         public static IAmAProducerRegistry Merge(this IAmAProducerRegistry lhs, IAmAProducerRegistry rhs)
         {
+            if (rhs == null)
+                return lhs;
+
+            if (lhs == null)
+                return rhs;
+
             var producers = 
                 lhs
                 .KeyedProducers.Concat(rhs.KeyedProducers)

diff --git a/tests/Paramore.Brighter.Core.Tests/CommandProcessors/When_Merging_Two_Producer_Registries.cs b/tests/Paramore.Brighter.Core.Tests/CommandProcessors/When_Merging_Two_Producer_Registries.cs
@@ -28,4 +28,72 @@ public void When_Merging_Two_Producer_Registries()
         producerRegistry.LookupBy("TestTwo").Should().NotBeNull();
 
     }
+
+    [Fact]
+    public void When_Merging_With_A_Null__Rhs_Registry()
+    {
+        var producerRegistryOne = new ProducerRegistry(
+            new Dictionary<string, IAmAMessageProducer>{{"TestOne", new FakeMessageProducer()}}
+        );
+
+        //act
+        var producerRegistry = producerRegistryOne.Merge(null);
+
+        //assert
+        producerRegistry.LookupBy("TestOne").Should().NotBeNull();
+
+    }
+
+    [Fact]
+    public void When_Merging_With_A_Null__Lhs_Registry()
+    {
+        //arrange
+        var producerRegistryTwo = new ProducerRegistry(
+            new Dictionary<string, IAmAMessageProducer>{{"TestTwo", new FakeMessageProducer()}}
+        );
+
+        //act
+        var producerRegistry =ProducerRegistryExtensions.Merge(null, producerRegistryTwo);
+
+        //assert
+        producerRegistry.LookupBy("TestTwo").Should().NotBeNull();
+
+    }
+
+    [Fact]
+    public void When_Merging_With_An_Empty_Rhs_Registry()
+    {
+        //arrange
+        var producerRegistryOne = new ProducerRegistry(
+            new Dictionary<string, IAmAMessageProducer>{{"TestOne", new FakeMessageProducer()}}
+        );
+
+        var producerRegistryTwo = new ProducerRegistry(new Dictionary<string, IAmAMessageProducer>());
+
+        //act
+        var producerRegistry = producerRegistryOne.Merge(producerRegistryTwo);
+
+        //assert
+        producerRegistry.LookupBy("TestOne").Should().NotBeNull();
+
+    }
+
+    [Fact]
+    public void When_Merging_With_An_Empty_Lhs_Registry()
+    {
+        //arrange
+        var producerRegistryOne = new ProducerRegistry(new Dictionary<string, IAmAMessageProducer>());
+
+        var producerRegistryTwo = new ProducerRegistry(
+            new Dictionary<string, IAmAMessageProducer>{{"TestTwo", new FakeMessageProducer()}}
+        );
+
+        //act
+        var producerRegistry = producerRegistryOne.Merge(producerRegistryTwo);
+
+        //assert
+        producerRegistry.LookupBy("TestTwo").Should().NotBeNull();
+
+    }
+
 }