Add integration tests for enumerables with projection to arrays (#7290)

* Add integration tests for enumerables with projection to arrays

Introduce integration tests to verify the conversion of a Select-projected IEnumerable to an array using JavaScript execution. This includes creating new test cases, activities, and workflows to ensure the end-to-end process behaves as expected. Also refined type inference in `ExpressionExecutionContextExtensions` for projection operators.

* Remove unused newline in EnumerableProjectionTests

src/modules/Elsa.Workflows.Core/Extensions/ExpressionExecutionContextExtensions.cs

@@ -556,7 +556,9 @@ public static class ExpressionExecutionContextExtensions
             return obj;
 
         // Use LINQ to convert the IEnumerable to an array.
-        var elementType = obj.GetType().GetGenericArguments().FirstOrDefault();
+        // For projection operators like Select, the element type is the LAST generic argument
+        // (e.g., ListSelectIterator<TSource, TResult> where TResult is the element type)
+        var elementType = obj.GetType().GetGenericArguments().LastOrDefault();
 
         if (elementType == null)
             return obj;

test/integration/Elsa.Workflows.IntegrationTests/Scenarios/ProjectedEnumerableToArray/EnumerableProjectionTestWorkflow.cs

@@ -0,0 +1,38 @@
+using Elsa.Expressions.JavaScript.Activities;
+using Elsa.Extensions;
+using Elsa.Workflows.Activities;
+using Elsa.Workflows.Memory;
+
+namespace Elsa.Workflows.IntegrationTests.Scenarios.ProjectedEnumerableToArray;
+
+/// <summary>
+/// Code-first workflow that reproduces the "projected IEnumerable to array" scenario end-to-end.
+/// </summary>
+public class EnumerableProjectionTestWorkflow : WorkflowBase
+{
+    protected override void Build(IWorkflowBuilder workflow)
+    {
+        // Store in workflow instance state to mimic real execution behavior.
+        var messagesVar = new Variable<object>("Messages", Array.Empty<string>()).WithWorkflowStorage();
+
+        workflow.WithVariables(messagesVar);
+
+        workflow.Root = new Sequence
+        {
+            Activities =
+            {
+                new TestEnumerableActivity
+                {
+                    EnumerableResult = new(messagesVar)
+                },
+
+                new RunJavaScript
+                {
+                    // Accessing Messages through JS triggers the conversion logic.
+                    Script = new("return getMessages();"),
+                    Result = new(messagesVar)
+                }
+            }
+        };
+    }
+}

test/integration/Elsa.Workflows.IntegrationTests/Scenarios/ProjectedEnumerableToArray/EnumerableProjectionTests.cs

@@ -0,0 +1,37 @@
+using Elsa.Expressions.Helpers;
+using Elsa.Testing.Shared;
+using Elsa.Workflows.Management;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit.Abstractions;
+
+namespace Elsa.Workflows.IntegrationTests.Scenarios.ProjectedEnumerableToArray;
+
+public class EnumerableProjectionTests(ITestOutputHelper testOutputHelper)
+{
+    private readonly WorkflowTestFixture _fixture = new(testOutputHelper);
+
+    [Fact(DisplayName = "JavaScript should convert a Select-projected IEnumerable variable to an array")]
+    public async Task Should_Convert_Select_Projected_Enumerable_To_Array()
+    {
+        // Arrange
+        var workflow = new EnumerableProjectionTestWorkflow();
+
+        // Act
+        var result = await _fixture.RunWorkflowAsync(workflow);
+
+        // Assert
+        Assert.Equal(WorkflowSubStatus.Finished, result.WorkflowState.SubStatus); // If conversion failed, workflow will have faulted.
+        var variableManager = _fixture.Services.GetRequiredService<IWorkflowInstanceVariableManager>();
+        var messagesVariable = (await variableManager.GetVariablesAsync(result.WorkflowExecutionContext)).FirstOrDefault(x => x.Variable.Name == "Messages");
+        var messages = messagesVariable?.Value.ConvertTo<string[]>();
+        
+        Assert.NotNull(messages);
+        Assert.Equal(5, messages.Length);
+
+        Assert.All(messages, message =>
+        {
+            Assert.Contains("Name:", message);
+            Assert.Contains("ID:", message);
+        });
+    }
+}

test/integration/Elsa.Workflows.IntegrationTests/Scenarios/ProjectedEnumerableToArray/TestEnumerableActivity.cs

@@ -0,0 +1,27 @@
+using Elsa.Workflows.Models;
+
+namespace Elsa.Workflows.IntegrationTests.Scenarios.ProjectedEnumerableToArray;
+
+/// <summary>
+/// A test activity that produces an IEnumerable&lt;string&gt; via Select projection, which has two generic arguments and was triggering the bug in ConvertIEnumerableToArray.
+/// </summary>
+public class TestEnumerableActivity : Activity
+{
+    public Output<object?> EnumerableResult { get; set; } = new();
+
+    protected override ValueTask ExecuteAsync(ActivityExecutionContext context)
+    {
+        // Create a list of items
+        var items = Enumerable
+            .Range(1, 5)
+            .Select(x => new TestOutputItem())
+            .ToList();
+
+        // Use Select to project to strings - this creates a ListSelectIterator<TestOutputItem, string>
+        // which has TWO generic arguments, triggering the bug
+        var messages = items.Select(e => $"Name: {e.Name} ID: {e.Id}");
+
+        context.Set(EnumerableResult, messages);
+        return context.CompleteActivityWithOutcomesAsync("Done");
+    }
+}

test/integration/Elsa.Workflows.IntegrationTests/Scenarios/ProjectedEnumerableToArray/TestOutputItem.cs

@@ -0,0 +1,7 @@
+namespace Elsa.Workflows.IntegrationTests.Scenarios.ProjectedEnumerableToArray;
+
+public class TestOutputItem
+{
+    public string Name { get; } = Guid.NewGuid().ToString();
+    public string Id { get; } = Guid.NewGuid().ToString();
+}

test/unit/Elsa.Workflows.Core.UnitTests/Extensions/ExpressionExecutionContextExtensions/ExpressionExecutionContextExtensionsTests.cs

@@ -1,5 +1,8 @@
+using Elsa.Expressions.JavaScript.Activities;
 using Elsa.Expressions.Models;
 using Elsa.Extensions;
+using Elsa.Testing.Shared;
+using Elsa.Workflows.Activities;
 using Elsa.Workflows.Memory;
 
 namespace Elsa.Workflows.Core.UnitTests;
@@ -13,7 +16,7 @@ public class ExpressionExecutionContextExtensionsTests
         var variable = new Variable("test", 5);
         var memoryRegister = new MemoryRegister(new Dictionary<string, MemoryBlock>
         {
-            { variable.Id, new MemoryBlock(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
+            { variable.Id, new(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
         });
 
         var context = new ExpressionExecutionContext(null!, memoryRegister);
@@ -46,7 +49,7 @@ public class ExpressionExecutionContextExtensionsTests
         var variable = new Variable("test", 5);
         var memoryRegister = new MemoryRegister(new Dictionary<string, MemoryBlock>
         {
-            { variable.Id, new MemoryBlock(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
+            { variable.Id, new(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
         });
 
         var context = new ExpressionExecutionContext(null!, memoryRegister);
@@ -92,7 +95,7 @@ public class ExpressionExecutionContextExtensionsTests
         var variable = new Variable("test", 5);
         var memoryRegister = new MemoryRegister(new Dictionary<string, MemoryBlock>
         {
-            { variable.Id, new MemoryBlock(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
+            { variable.Id, new(variable.Value, new VariableBlockMetadata(variable, typeof(object), true)) }
         });
 
         var context = new ExpressionExecutionContext(null!, memoryRegister);