diff --git a/Contracts/Synergy.Contracts.Test/Failures/Because/Fail.Because.cs b/Contracts/Synergy.Contracts.Test/Failures/Because/Fail.Because.cs
new file mode 100644
index 0000000..f7b66b0
--- /dev/null
+++ b/Contracts/Synergy.Contracts.Test/Failures/Because/Fail.Because.cs
@@ -0,0 +1,80 @@
+using Synergy.Contracts.Samples.Domain;
+using Xunit;
+
+namespace Synergy.Contracts.Test.Failures.Because;
+
+public class FailBecauseTest
+{
+    [Fact]
+    public void BecauseWith0Arguments()
+    {
+        // ACT
+        var exception = Fail.Because("Always");
+
+        // ASSERT
+        Assert.NotNull(exception);
+        Assert.Equal("Always", exception.Message);
+    }
+
+    [Fact]
+    public void BecauseWith1Argument()
+    {
+        // ACT
+        // ReSharper disable once HeapView.BoxingAllocation
+        var exception = Fail.Because("Always {0}", 1);
+
+        // ASSERT
+        Assert.NotNull(exception);
+        Assert.Equal("Always 1", exception.Message);
+    }
+
+    [Fact]
+    public void BecauseWith2Arguments()
+    {
+        // ACT
+        // ReSharper disable once HeapView.BoxingAllocation
+        var exception = Fail.Because("Always {0} {1}", "fails", 1);
+
+        // ASSERT
+        Assert.NotNull(exception);
+        Assert.Equal("Always fails 1", exception.Message);
+    }
+
+    [Fact]
+    public void BecauseWith3Arguments()
+    {
+        // ACT
+        // ReSharper disable once HeapView.BoxingAllocation
+        var exception = Fail.Because("Always {0} {1} {2}", "fails", 1, "times");
+
+        // ASSERT
+        Assert.NotNull(exception);
+        Assert.Equal("Always fails 1 times", exception.Message);
+    }
+
+    [Fact]
+    public void BecauseWithNArguments()
+    {
+        // ACT
+        // ReSharper disable once HeapView.BoxingAllocation
+        var exception = Fail.Because("Always {0} {1} {2} {3}", "fails", 1, "times", "frequently");
+
+        // ASSERT
+        Assert.NotNull(exception);
+        Assert.Equal("Always fails 1 times frequently", exception.Message);
+    }
+
+    [Fact]
+    public void BecauseSample()
+    {
+        // ARRANGE
+        var contractor = new Contractor();
+
+        // ACT
+        var exception = Assert.Throws<DesignByContractViolationException>(
+            () => contractor.SetPersonName("Marcin", "Celej"));
+
+        // ASSERT
+        Assert.Equal("Not implemented yet", exception.Message);
+    }
+}
\ No newline at end of file
diff --git a/Contracts/Synergy.Contracts.Test/Failures/FailBecauseTest.cs b/Contracts/Synergy.Contracts.Test/Failures/FailBecauseTest.cs
deleted file mode 100644
index 5d56427..0000000
--- a/Contracts/Synergy.Contracts.Test/Failures/FailBecauseTest.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-using NUnit.Framework;
-
-namespace Synergy.Contracts.Test.Failures
-{
-    [TestFixture]
-    public class FailBecauseTest
-    {
-        [Test]
-        public void fail_because_message()
-        {
-            // ACT
-            var exception = Fail.Because("failure description");
-
-            // ASSERT
-            Assert.That(exception.Message, Is.EqualTo("failure description"));
-        }
-    }
-}
\ No newline at end of file
diff --git a/Contracts/Synergy.Contracts.Test/Failures/FailTest.cs b/Contracts/Synergy.Contracts.Test/Failures/FailTest.cs
deleted file mode 100644
index 669e7ed..0000000
--- a/Contracts/Synergy.Contracts.Test/Failures/FailTest.cs
+++ /dev/null
@@ -1,86 +0,0 @@
-using NUnit.Framework;
-using Synergy.Contracts.Samples.Domain;
-
-namespace Synergy.Contracts.Test.Failures
-{
-    [TestFixture]
-    public class FailTest
-    {
-        #region Fail.Because
-
-        [Test]
-        public void BecauseWith0Arguments()
-        {
-            // ACT
-            DesignByContractViolationException exception = Fail.Because("Always");
-
-            // ASSERT
-            Assert.That(exception, Is.Not.Null);
-            Assert.That(exception.Message, Is.EqualTo("Always"));
-        }
-
-        [Test]
-        public void BecauseWith1Argument()
-        {
-            // ACT
-            // ReSharper disable once HeapView.BoxingAllocation
-            DesignByContractViolationException exception = Fail.Because("Always {0}", 1);
-
-            // ASSERT
-            Assert.That(exception, Is.Not.Null);
-            Assert.That(exception.Message, Is.EqualTo("Always 1"));
-        }
-
-        [Test]
-        public void BecauseWith2Arguments()
-        {
-            // ACT
-            // ReSharper disable once HeapView.BoxingAllocation
-            DesignByContractViolationException exception = Fail.Because("Always {0} {1}", "fails", 1);
-
-            // ASSERT
-            Assert.That(exception, Is.Not.Null);
-            Assert.That(exception.Message, Is.EqualTo("Always fails 1"));
-        }
-
-        [Test]
-        public void BecauseWith3Arguments()
-        {
-            // ACT
-            // ReSharper disable once HeapView.BoxingAllocation
-            DesignByContractViolationException exception = Fail.Because("Always {0} {1} {2}", "fails", 1, "times");
-
-            // ASSERT
-            Assert.That(exception, Is.Not.Null);
-            Assert.That(exception.Message, Is.EqualTo("Always fails 1 times"));
-        }
-
-        [Test]
-        public void BecauseWithNArguments()
-        {
-            // ACT
-            // ReSharper disable once HeapView.BoxingAllocation
-            DesignByContractViolationException exception = Fail.Because("Always {0} {1} {2} {3}", "fails", 1, "times", "frequently");
-
-            // ASSERT
-            Assert.That(exception, Is.Not.Null);
-            Assert.That(exception.Message, Is.EqualTo("Always fails 1 times frequently"));
-        }
-
-        [Test]
-        public void BecauseSample()
-        {
-            // ARRANGE
-            var contractor = new Contractor();
-
-            // ACT
-            var exception = Assert.Throws<DesignByContractViolationException>(
-                () => contractor.SetPersonName("Marcin", "Celej"));
-
-            // ASSERT
-            Assert.That(exception.Message, Is.EqualTo("Not implemented yet"));
-        }
-
-        #endregion
-    }
-}
\ No newline at end of file