Fixed code.

src/Core/Models/Commands/CommandResult.cs

@@ -51,7 +51,8 @@ public class Partial<T> : CommandResult<T>
 
     public Partial(IEnumerable<T> successfulItems, IEnumerable<Error<T>> failedItems)
     {
-
+        Successes = successfulItems.ToArray();
+        Failures = failedItems.ToArray();
     }
 }
 

test/Core.Test/Models/Commands/CommandResultTests.cs

@@ -41,6 +41,12 @@ public class CommandResultTests
 
         var result = BulkAction(listOfRecords);
 
-        Assert.IsType<Partial<TestItem>>(listOfRecords);
+        Assert.IsType<Partial<TestItem>>(result);
+
+        var failures = (result as Partial<TestItem>).Failures.ToArray();
+        var success = (result as Partial<TestItem>).Successes.First();
+
+        Assert.Equal(listOfRecords.First(), success);
+        Assert.Equal(2, failures.Length);
     }
 }