Adds a helper method to simplify the verification of dependencies

ArchUnitNET/Fluent/Dependencies.cs

@@ -0,0 +1,36 @@
+// Copyright 2019 Florian Gather <[email protected]>
+// 	Copyright 2019 Fritz Brandhuber <[email protected]>
+// 	Copyright 2020 Pavel Fischer <[email protected]>
+// 
+// 	SPDX-License-Identifier: Apache-2.0
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using static ArchUnitNET.Fluent.ArchRuleDefinition;
+
+namespace ArchUnitNET.Fluent
+{
+    public static class Dependencies
+    {
+        /// <summary>
+        /// Verifies that a source assembly only depends on a set of target assemblies.
+        /// </summary>
+        /// <param name="source">The source assembly</param>
+        /// <param name="target">The assemblies which are allowed to be used from the source assembly</param>
+        public static IArchRule Check(Assembly source, IEnumerable<Assembly> target)
+        {
+            var allowedTypes = Types().That().ResideInAssembly(source);
+            allowedTypes =
+                target.Aggregate(allowedTypes, (current, assembly) => current.Or().ResideInAssembly(assembly));
+
+            var rule = Types()
+                .That()
+                .ResideInAssembly(source)
+                .Should()
+                .OnlyDependOn(allowedTypes);
+
+            return rule;
+        }
+    }
+}