diff --git a/src/common/Elsa.Testing.Shared.Integration/WorkflowTestFixture.cs b/src/common/Elsa.Testing.Shared.Integration/WorkflowTestFixture.cs
new file mode 100644
index 000000000..8bf03ab4c
--- /dev/null
+++ b/src/common/Elsa.Testing.Shared.Integration/WorkflowTestFixture.cs
@@ -0,0 +1,155 @@
+using Elsa.Extensions;
+using Elsa.Features.Services;
+using Elsa.Workflows;
+using Elsa.Workflows.Activities;
+using Elsa.Workflows.Models;
+using Elsa.Workflows.State;
+using JetBrains.Annotations;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit.Abstractions;
+
+namespace Elsa.Testing.Shared;
+
+/// <summary>
+/// A test fixture for integration testing workflows and activities.
+/// Provides a fluent API to configure services, run workflows, and capture output.
+/// </summary>
+public class WorkflowTestFixture
+{
+    private readonly TestApplicationBuilder _testApplicationBuilder;
+    private IServiceProvider? _services;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WorkflowTestFixture"/> class.
+    /// </summary>
+    /// <param name="testOutputHelper">The test output helper</param>
+    public WorkflowTestFixture(ITestOutputHelper testOutputHelper)
+    {
+        _testApplicationBuilder = new TestApplicationBuilder(testOutputHelper);
+        CapturingTextWriter = new CapturingTextWriter();
+        _testApplicationBuilder.WithCapturingTextWriter(CapturingTextWriter);
+    }
+
+    /// <summary>
+    /// Gets the capturing text writer that captures standard output from WriteLine activities.
+    /// </summary>
+    public CapturingTextWriter CapturingTextWriter { get; }
+
+    /// <summary>
+    /// Gets the service provider. Throws if Build() hasn't been called yet.
+    /// </summary>
+    private IServiceProvider Services => _services ?? throw new InvalidOperationException("Build() must be called before accessing services");
+
+    /// <summary>
+    /// Configures Elsa features.
+    /// </summary>
+    /// <param name="configure">Action to configure Elsa</param>
+    /// <returns>The fixture instance for method chaining</returns>
+    [UsedImplicitly]
+    public WorkflowTestFixture ConfigureElsa(Action<IModule> configure)
+    {
+        _testApplicationBuilder.ConfigureElsa(configure);
+        return this;
+    }
+
+    /// <summary>
+    /// Configures the service collection.
+    /// </summary>
+    /// <param name="configure">Action to configure the service collection</param>
+    /// <returns>The fixture instance for method chaining</returns>
+    [UsedImplicitly]
+    public WorkflowTestFixture ConfigureServices(Action<IServiceCollection> configure)
+    {
+        _testApplicationBuilder.ConfigureServices(configure);
+        return this;
+    }
+
+    /// <summary>
+    /// Adds a workflow to the service provider.
+    /// </summary>
+    [UsedImplicitly]
+    public WorkflowTestFixture AddWorkflow<T>() where T : IWorkflow
+    {
+        _testApplicationBuilder.AddWorkflow<T>();
+        return this;
+    }
+
+    /// <summary>
+    /// Adds activities from the assembly containing the specified type.
+    /// </summary>
+    [UsedImplicitly]
+    public WorkflowTestFixture AddActivitiesFrom<T>()
+    {
+        _testApplicationBuilder.AddActivitiesFrom<T>();
+        return this;
+    }
+
+    /// <summary>
+    /// Adds workflows from the specified relative directory.
+    /// </summary>
+    /// <param name="directory">The path segments of the directory</param>
+    [UsedImplicitly]
+    public WorkflowTestFixture WithWorkflowsFromDirectory(params string[] directory)
+    {
+        _testApplicationBuilder.WithWorkflowsFromDirectory(directory);
+        return this;
+    }
+
+    /// <summary>
+    /// Builds the service provider and populates registries.
+    /// Must be called before running workflows.
+    /// </summary>
+    public async Task<WorkflowTestFixture> BuildAsync()
+    {
+        _services = _testApplicationBuilder.Build();
+        await Services.PopulateRegistriesAsync();
+        return this;
+    }
+
+    /// <summary>
+    /// Runs a workflow and returns the workflow result.
+    /// Automatically builds the fixture if not already built.
+    /// </summary>
+    /// <param name="workflow">The workflow to run</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>The workflow result after execution</returns>
+    public async Task<RunWorkflowResult> RunWorkflowAsync(IWorkflow workflow, CancellationToken cancellationToken = default)
+    {
+        if (_services == null)
+            await BuildAsync();
+
+        var workflowRunner = Services.GetRequiredService<IWorkflowRunner>();
+        return await workflowRunner.RunAsync(workflow, cancellationToken: cancellationToken);
+    }
+
+    /// <summary>
+    /// Runs an activity wrapped in a workflow and returns the workflow result.
+    /// Automatically builds the fixture if not already built.
+    /// </summary>
+    /// <param name="activity">The activity to run</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>The workflow result after execution</returns>
+    public async Task<RunWorkflowResult> RunActivityAsync(IActivity activity, CancellationToken cancellationToken = default)
+    {
+        if (_services == null)
+            await BuildAsync();
+
+        var workflowRunner = Services.GetRequiredService<IWorkflowRunner>();
+        return await workflowRunner.RunAsync(activity, cancellationToken: cancellationToken);
+    }
+
+    /// <summary>
+    /// Runs a workflow by definition ID and returns the workflow state.
+    /// Automatically builds the fixture if not already built.
+    /// </summary>
+    /// <param name="definitionId">The workflow definition ID</param>
+    /// <param name="input">Optional input dictionary</param>
+    /// <returns>The workflow state after execution</returns>
+    public async Task<WorkflowState> RunWorkflowAsync(string definitionId, IDictionary<string, object>? input = null)
+    {
+        if (_services == null)
+            await BuildAsync();
+
+        return await Services.RunWorkflowUntilEndAsync(definitionId, input);
+    }
+}
diff --git a/src/modules/Elsa.Expressions.JavaScript/Activities/RunJavaScript/RunJavaScript.cs b/src/modules/Elsa.Expressions.JavaScript/Activities/RunJavaScript/RunJavaScript.cs
index ff5400cfe..60680387b 100644
--- a/src/modules/Elsa.Expressions.JavaScript/Activities/RunJavaScript/RunJavaScript.cs
+++ b/src/modules/Elsa.Expressions.JavaScript/Activities/RunJavaScript/RunJavaScript.cs
@@ -25,7 +25,7 @@ public class RunJavaScript : CodeActivity<object?>
     /// <inheritdoc />
     public RunJavaScript(string script, [CallerFilePath] string? source = null, [CallerLineNumber] int? line = null) : this(source, line)
     {
-        Script = new Input<string>(script);
+        Script = new(script);
     }
 
     /// <summary>
diff --git a/test/integration/Elsa.JavaScript.IntegrationTests/JsonConverterTest.cs b/test/integration/Elsa.JavaScript.IntegrationTests/JsonConverterTest.cs
index e1d080af5..ac82f2a1b 100644
--- a/test/integration/Elsa.JavaScript.IntegrationTests/JsonConverterTest.cs
+++ b/test/integration/Elsa.JavaScript.IntegrationTests/JsonConverterTest.cs
@@ -2,14 +2,13 @@
 using System.Numerics;
 using System.Text.Json;
 using Elsa.Common.Converters;
-using Elsa.Expressions.Models;
 using Elsa.Expressions.JavaScript.Contracts;
+using Elsa.Expressions.Models;
 using Elsa.Testing.Shared;
 using Microsoft.Extensions.DependencyInjection;
-using Xunit;
 using Xunit.Abstractions;
 
-namespace Elsa.Expressions.JavaScript.IntegrationTests;
+namespace Elsa.JavaScript.IntegrationTests;
 public class JsonConverterTest(ITestOutputHelper testOutputHelper)
 {
     private readonly IServiceProvider _serviceProvider = new TestApplicationBuilder(testOutputHelper).Build();
@@ -23,7 +22,7 @@ public class JsonConverterTest(ITestOutputHelper testOutputHelper)
 }";
         var expressionExecutionContext = new ExpressionExecutionContext(_serviceProvider, new MemoryRegister());
         var result = (await javaScriptEvaluator.EvaluateAsync(script, typeof(ExpandoObject), expressionExecutionContext))!;
-        var options = new JsonSerializerOptions()
+        var options = new JsonSerializerOptions
         {
             Converters = { new BigIntegerJsonConverter() }
         };
@@ -47,9 +46,9 @@ public class JsonConverterTest(ITestOutputHelper testOutputHelper)
     }
 
     [Fact(DisplayName = "BigIntegerJsonConverter Deserialize")]
-    public async Task Test3()
+    public Task Test3()
     {
-        var options = new JsonSerializerOptions()
+        var options = new JsonSerializerOptions
         {
             Converters = { new BigIntegerJsonConverter() }
         };
@@ -57,5 +56,6 @@ public class JsonConverterTest(ITestOutputHelper testOutputHelper)
         BigInteger bigInteger = JsonSerializer.Deserialize<BigInteger>("7239948466988781569", options);
 
         Assert.Equal(7239948466988781569, bigInteger);
+        return Task.CompletedTask;
     }
 }
diff --git a/test/integration/Elsa.JavaScript.IntegrationTests/JsonElementConverterTests.cs b/test/integration/Elsa.JavaScript.IntegrationTests/JsonElementConverterTests.cs
index fb490adcb..85aa4b984 100644
--- a/test/integration/Elsa.JavaScript.IntegrationTests/JsonElementConverterTests.cs
+++ b/test/integration/Elsa.JavaScript.IntegrationTests/JsonElementConverterTests.cs
@@ -1,13 +1,12 @@
 using System.Text.Json;
-using Elsa.Expressions.Models;
 using Elsa.Expressions.JavaScript.Contracts;
+using Elsa.Expressions.Models;
 using Elsa.Testing.Shared;
 using Elsa.Workflows.Memory;
 using Microsoft.Extensions.DependencyInjection;
-using Xunit;
 using Xunit.Abstractions;
 
-namespace Elsa.Expressions.JavaScript.IntegrationTests;
+namespace Elsa.JavaScript.IntegrationTests;
 
 public class JsonElementConverterTests(ITestOutputHelper testOutputHelper)
 {
diff --git a/test/integration/Elsa.JavaScript.IntegrationTests/RunJavaScriptTests.cs b/test/integration/Elsa.JavaScript.IntegrationTests/RunJavaScriptTests.cs
new file mode 100644
index 000000000..0e3ca8281
--- /dev/null
+++ b/test/integration/Elsa.JavaScript.IntegrationTests/RunJavaScriptTests.cs
@@ -0,0 +1,101 @@
+using Elsa.Expressions.JavaScript.Activities;
+using Elsa.Testing.Shared;
+using Elsa.Workflows.Activities;
+using Elsa.Workflows.Memory;
+using Xunit.Abstractions;
+
+namespace Elsa.JavaScript.IntegrationTests;
+
+public class RunJavaScriptTests(ITestOutputHelper testOutputHelper)
+{
+    private readonly WorkflowTestFixture _fixture = new(testOutputHelper);
+
+    [Theory(DisplayName = "RunJavaScript should execute valid scripts successfully")]
+    [InlineData("return 1 + 1;")]
+    [InlineData("return 'Hello World';")]
+    [InlineData("return 42;")]
+    public async Task Should_Execute_Valid_Scripts(string script)
+    {
+        // Arrange
+        var activity = new RunJavaScript { Script = new(script), Result = new() };
+
+        // Act
+        await _fixture.RunActivityAsync(activity);
+
+        // Assert
+        Assert.Empty(_fixture.CapturingTextWriter.Lines);
+    }
+
+    [Theory(DisplayName = "RunJavaScript should set outcomes correctly")]
+    [InlineData("setOutcome('Success');")]
+    [InlineData("setOutcomes(['Branch1', 'Branch2', 'Branch3']);")]
+    public async Task Should_Set_Outcomes(string script)
+    {
+        // Arrange
+        var activity = new RunJavaScript { Script = new(script) };
+
+        // Act
+        await _fixture.RunActivityAsync(activity);
+
+        // Assert
+        Assert.Null(_fixture.CapturingTextWriter.Lines.FirstOrDefault());
+    }
+
+    [Theory(DisplayName = "RunJavaScript should not execute invalid scripts")]
+    [InlineData("")]
+    [InlineData("   ")]
+    public async Task Should_Not_Execute_Invalid_Scripts(string script)
+    {
+        // Arrange
+        var activity = new RunJavaScript { Script = new(script), Result = new() };
+
+        // Act
+        await _fixture.RunActivityAsync(activity);
+
+        // Assert
+        Assert.Empty(_fixture.CapturingTextWriter.Lines);
+    }
+
+    [Fact(DisplayName = "RunJavaScript should access workflow variables")]
+    public async Task Should_Access_Workflow_Variables()
+    {
+        // Arrange
+        var myVar = new Variable<int>("MyVar", 100);
+        var script = "return getMyVar();";
+        var workflow = new Workflow
+        {
+            Root = new RunJavaScript { Script = new(script), Result = new() },
+            Variables = { myVar }
+        };
+
+        // Act
+        await _fixture.RunActivityAsync(workflow);
+
+        // Assert - workflow completes successfully
+        Assert.Empty(_fixture.CapturingTextWriter.Lines);
+    }
+
+    [Fact(DisplayName = "RunJavaScript should execute complex script with multiple statements and outcomes")]
+    public async Task Should_Execute_Complex_Script_With_Multiple_Statements()
+    {
+        // Arrange
+        var script = @"
+            var x = 10;
+            var y = 20;
+            var sum = x + y;
+            if (sum > 25) {
+                setOutcome('Large');
+            } else {
+                setOutcome('Small');
+            }
+            return sum;
+        ";
+        var activity = new RunJavaScript { Script = new(script), Result = new() };
+
+        // Act
+        await _fixture.RunActivityAsync(activity);
+
+        // Assert - workflow completes successfully
+        Assert.Empty(_fixture.CapturingTextWriter.Lines);
+    }
+}
diff --git a/test/integration/Elsa.JavaScript.IntegrationTests/ToJsonTests.cs b/test/integration/Elsa.JavaScript.IntegrationTests/ToJsonTests.cs
index 384b4ec0d..a75525c1b 100644
--- a/test/integration/Elsa.JavaScript.IntegrationTests/ToJsonTests.cs
+++ b/test/integration/Elsa.JavaScript.IntegrationTests/ToJsonTests.cs
@@ -1,13 +1,12 @@
 using System.Text.Json;
-using Elsa.Expressions.Models;
 using Elsa.Expressions.JavaScript.Contracts;
+using Elsa.Expressions.Models;
 using Elsa.Testing.Shared;
 using Elsa.Workflows.Memory;
 using Microsoft.Extensions.DependencyInjection;
-using Xunit;
 using Xunit.Abstractions;
 
-namespace Elsa.Expressions.JavaScript.IntegrationTests;
+namespace Elsa.JavaScript.IntegrationTests;
 
 public class ToJsonTests(ITestOutputHelper testOutputHelper)
 {
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Activities/Fork/ForkTests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Activities/Fork/ForkTests.cs
index 33239e612..ffabf4de1 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Activities/Fork/ForkTests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Activities/Fork/ForkTests.cs
@@ -11,7 +11,7 @@ public class ForkTests
     private readonly IWorkflowRunner _workflowRunner;
     private readonly CapturingTextWriter _capturingTextWriter = new();
     private readonly IWorkflowBuilderFactory _workflowBuilderFactory;
-    private IServiceProvider _services;
+    private readonly IServiceProvider _services;
 
     public ForkTests(ITestOutputHelper testOutputHelper)
     {