pythonnet · fdanny · Dec 1, 2016 · Dec 2, 2016 · Dec 2, 2016
diff --git a/src/runtime/assemblymanager.cs b/src/runtime/assemblymanager.cs
@@ -338,6 +338,38 @@ public static bool LoadImplicit(string name, bool warn = true)
             return loaded;
         }
 
+        //===================================================================
+        // Return the Assembly for a given name
+        //===================================================================
+        internal static Assembly GetAssembly(string name)
+        {
+            string[] names = name.Split('.');
+            string s = "";
+            HashSet<Assembly> assembliesSet = null;
+            for (int i = 0; i < names.Length; i++)
+            {
+                s = (i == 0) ? names[0] : s + "." + names[i];
+                if (assembliesSet == null)
+                {
+                    assembliesSet = new HashSet<Assembly>(AppDomain.CurrentDomain.GetAssemblies());
+                }
+                Assembly a = FindLoadedAssembly(s);
+                if (a == null)
+                {
+                    a = LoadAssemblyPath(s);
+                }
+                if (a == null)
+                {
+                    a = LoadAssembly(s);
+                }
+                if (a != null && assembliesSet.Contains(a))
+                {
+                    return a;
+                }
+            }
+            return null;
+        }
+
 
         //===================================================================
         // Scans an assembly for exported namespaces, adding them to the

diff --git a/src/runtime/importhook.cs b/src/runtime/importhook.cs
@@ -278,7 +278,35 @@ public static IntPtr __import__(IntPtr self, IntPtr args, IntPtr kw)
                 {
                     // May be called when a module being imported imports a module.
                     // In particular, I've seen decimal import copy import org.python.core
-                    return Runtime.PyObject_Call(py_import, args, kw);
+                    var res = Runtime.PyObject_Call(py_import, args, kw);
+
+                    // Check if there is an ImportError Exception if so
+                    // determine which dependencies are missing
+                    if(Exceptions.ExceptionMatches(Exceptions.ImportError))
+                    {
+                        var target_assembly = AssemblyManager.GetAssembly(realname);
+                        if (target_assembly != null)
+                        {
+                            System.Collections.Generic.List<string> missing_dependencies = 
+                                new System.Collections.Generic.List<string>();
+                            foreach (var assembly in target_assembly.GetReferencedAssemblies())
+                            {
+                                var depedentAssembly = AssemblyManager.LoadAssembly(assembly.Name);
+                                if (depedentAssembly == null)
+                                    missing_dependencies.Add(assembly.Name);
+                            }
+
+                            if (missing_dependencies.Count > 0)
+                            {
+                                // We found missing dependencies
+                                string error = String.Format("No module named {0} missing dependencies {1}", 
+                                    realname, String.Join(", ", missing_dependencies));
+                                Exceptions.SetError(Exceptions.ImportError, error);
+                            }
+                        }                        
+                    }
+                    return res;
+
                 }
             }
 

diff --git a/src/tests/test_suite/TestDependencyAssembly.dll b/src/tests/test_suite/TestDependencyAssembly.dll
diff --git a/src/tests/test_suite/_missing_import_dependency.py b/src/tests/test_suite/_missing_import_dependency.py
@@ -0,0 +1,5 @@
+import os
+import clr
+path_to_dll = os.path.join(os.path.dirname(__file__), "TestDependencyAssembly.dll")
+clr.AddReference(path_to_dll)
+from TestDependencyAssembly import TestDependency
diff --git a/src/tests/test_suite/test_import.py b/src/tests/test_suite/test_import.py
@@ -9,6 +9,12 @@ def testRealtiveMissingImport(self):
             from . import _missing_import
         except ImportError:
             pass
+
+    def testMissingImportDepencency(self):
+        missing_dependency_name = "MissingDependencyAssembly"
+        with self.assertRaisesRegexp(ImportError, missing_dependency_name):
+             from . import _missing_import_dependency
+
 
 
 def test_suite():