Index: Ringtoets/Integration/src/Ringtoets.Integration.Service/Merge/AssessmentSectionProviderActivity.cs
===================================================================
diff -u -rc7a1a30a7fafe8671a06b10bf2a3d56cf9f510a4 -reb36d0a34bdea2d82aabec9f649516dac00a648a
--- Ringtoets/Integration/src/Ringtoets.Integration.Service/Merge/AssessmentSectionProviderActivity.cs	(.../AssessmentSectionProviderActivity.cs)	(revision c7a1a30a7fafe8671a06b10bf2a3d56cf9f510a4)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Service/Merge/AssessmentSectionProviderActivity.cs	(.../AssessmentSectionProviderActivity.cs)	(revision eb36d0a34bdea2d82aabec9f649516dac00a648a)
@@ -1,8 +1,14 @@
-using Core.Common.Base.Service;
+using System;
+using Core.Common.Base.Service;
+using Ringtoets.Integration.Data;
 using Ringtoets.Integration.Data.Merge;
 
 namespace Ringtoets.Integration.Service.Merge
 {
+    /// <summary>
+    /// Activity to retrieve a collection of <see cref="AssessmentSection"/>
+    /// from a file.
+    /// </summary>
     public class AssessmentSectionProviderActivity : Activity
     {
         private readonly AssessmentSectionsOwner owner;
@@ -11,10 +17,35 @@
 
         private bool canceled;
 
+        /// <summary>
+        /// Creates a new instance of <see cref="AssessmentSectionProviderActivity"/>.
+        /// </summary>
+        /// <param name="owner">The owner to set the retrieved collection
+        /// of <see cref="AssessmentSection"/> on.</param>
+        /// <param name="assessmentSectionProvider">The provider defining how to
+        /// retrieve the collection of <see cref="AssessmentSection"/> from a file.</param>
+        /// <param name="filePath">The file path to retrieve the collection of
+        /// <see cref="AssessmentSection"/> from.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any of the arguments is <c>null</c>.</exception>
         public AssessmentSectionProviderActivity(AssessmentSectionsOwner owner,
                                                  IAssessmentSectionProvider assessmentSectionProvider,
                                                  string filePath)
         {
+            if (owner == null)
+            {
+                throw new ArgumentNullException(nameof(owner));
+            }
+
+            if (assessmentSectionProvider == null)
+            {
+                throw new ArgumentNullException(nameof(assessmentSectionProvider));
+            }
+
+            if (filePath == null)
+            {
+                throw new ArgumentNullException(nameof(filePath));
+            }
+
             this.owner = owner;
             this.assessmentSectionProvider = assessmentSectionProvider;
             this.filePath = filePath;
Index: Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/Merge/AssessmentSectionProviderActivityTest.cs
===================================================================
diff -u -rc7a1a30a7fafe8671a06b10bf2a3d56cf9f510a4 -reb36d0a34bdea2d82aabec9f649516dac00a648a
--- Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/Merge/AssessmentSectionProviderActivityTest.cs	(.../AssessmentSectionProviderActivityTest.cs)	(revision c7a1a30a7fafe8671a06b10bf2a3d56cf9f510a4)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/Merge/AssessmentSectionProviderActivityTest.cs	(.../AssessmentSectionProviderActivityTest.cs)	(revision eb36d0a34bdea2d82aabec9f649516dac00a648a)
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 using Core.Common.Base.Service;
 using NUnit.Framework;
@@ -14,6 +15,53 @@
     public class AssessmentSectionProviderActivityTest
     {
         [Test]
+        public void Constructor_OwnerNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var provider = mocks.Stub<IAssessmentSectionProvider>();
+            mocks.ReplayAll();
+
+            // Call
+            TestDelegate call = () => new AssessmentSectionProviderActivity(null, provider, string.Empty);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("owner", exception.ParamName);
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void Constructor_ProviderNull_ThrowsArgumentNullException()
+        {
+            // Call
+            TestDelegate call = () => new AssessmentSectionProviderActivity(new AssessmentSectionsOwner(), null, string.Empty);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("assessmentSectionProvider", exception.ParamName);
+        }
+
+        [Test]
+        public void Constructor_FilePathNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var provider = mocks.Stub<IAssessmentSectionProvider>();
+            mocks.ReplayAll();
+
+            // Call
+            TestDelegate call = () => new AssessmentSectionProviderActivity(new AssessmentSectionsOwner(), 
+                                                                            provider, 
+                                                                            null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("filePath", exception.ParamName);
+            mocks.VerifyAll();
+        }
+        
+        [Test]
         public void Constructor_ExpectedValues()
         {
             // Setup
@@ -29,18 +77,18 @@
             // Assert
             Assert.IsInstanceOf<Activity>(activity);
             Assert.AreEqual(ActivityState.None, activity.State);
+            mocks.VerifyAll();
         }
 
         [Test]
-        public void Run_ProviderReturnsAssessmentSections_SetsActivityStateToExecutedAndSetsAssessmentSections()
+        public void Run_Always_SendsFilePathToGetsAssessmentSections()
         {
             // Setup
             const string filePath = "Path to file";
-            IEnumerable<AssessmentSection> assessmentSections = Enumerable.Empty<AssessmentSection>();
 
             var mocks = new MockRepository();
             var provider = mocks.Stub<IAssessmentSectionProvider>();
-            provider.Expect(p => p.GetAssessmentSections(filePath)).Return(assessmentSections);
+            provider.Expect(p => p.GetAssessmentSections(filePath)).Return(Enumerable.Empty<AssessmentSection>());
             mocks.ReplayAll();
 
             var owner = new AssessmentSectionsOwner();
@@ -50,46 +98,72 @@
             activity.Run();
 
             // Assert
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void Run_ProviderReturnsAssessmentSections_SetsActivityStateToExecutedAndSetsAssessmentSections()
+        {
+            // Setup
+            IEnumerable<AssessmentSection> assessmentSections = Enumerable.Empty<AssessmentSection>();
+
+            var mocks = new MockRepository();
+            var provider = mocks.Stub<IAssessmentSectionProvider>();
+            provider.Expect(p => p.GetAssessmentSections(null))
+                    .IgnoreArguments()
+                    .Return(assessmentSections);
+            mocks.ReplayAll();
+
+            var owner = new AssessmentSectionsOwner();
+            var activity = new AssessmentSectionProviderActivity(owner, provider, string.Empty);
+
+            // Call
+            activity.Run();
+
+            // Assert
             Assert.AreEqual(ActivityState.Executed, activity.State);
             Assert.AreSame(assessmentSections, owner.AssessmentSections);
+            mocks.VerifyAll();
         }
 
         [Test]
         public void Run_ProviderThrowsException_SetsActivityStateToFailedAndDoesNotSetAssessmentSections()
         {
             // Setup
-            const string filePath = "Path to file";
-
             var mocks = new MockRepository();
             var provider = mocks.Stub<IAssessmentSectionProvider>();
-            provider.Expect(p => p.GetAssessmentSections(filePath)).Throw(new AssessmentSectionProviderException());
+            provider.Expect(p => p.GetAssessmentSections(null))
+                    .IgnoreArguments()
+                    .Throw(new AssessmentSectionProviderException());
             mocks.ReplayAll();
 
             var owner = new AssessmentSectionsOwner();
-            var activity = new AssessmentSectionProviderActivity(owner, provider, filePath);
+            var activity = new AssessmentSectionProviderActivity(owner, provider, string.Empty);
 
             // Call
             activity.Run();
 
             // Assert
             Assert.AreEqual(ActivityState.Failed, activity.State);
             Assert.IsNull(owner.AssessmentSections);
+            mocks.VerifyAll();
         }
 
         [Test]
         public void GivenCancelledActivity_WhenFinishingActivity_ThenActivityStateSetToCancelledAndDoesNotSetAssessmentSections()
         {
             // Given
-            const string filePath = "Path to file";
             IEnumerable<AssessmentSection> assessmentSections = Enumerable.Empty<AssessmentSection>();
 
             var mocks = new MockRepository();
             var provider = mocks.Stub<IAssessmentSectionProvider>();
-            provider.Expect(p => p.GetAssessmentSections(filePath)).Return(assessmentSections);
+            provider.Expect(p => p.GetAssessmentSections(null))
+                    .IgnoreArguments()
+                    .Return(assessmentSections);
             mocks.ReplayAll();
 
             var owner = new AssessmentSectionsOwner();
-            var activity = new AssessmentSectionProviderActivity(owner, provider, filePath);
+            var activity = new AssessmentSectionProviderActivity(owner, provider, string.Empty);
 
             activity.Run();
             activity.Cancel();
@@ -100,6 +174,7 @@
             // Assert
             Assert.AreEqual(ActivityState.Canceled, activity.State);
             Assert.IsNull(owner.AssessmentSections);
+            mocks.VerifyAll();
         }
     }
 }
\ No newline at end of file