How to reproduce:

1. Open attached project
2. Open the Editor Tests Runner window
3. Right click any test and select Open in Editor
- Note an error is thrown in the console:

AssemblyResolutionException: Failed to resolve assembly: 'Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'
Mono.Cecil.BaseAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.BaseAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name)
Mono.Cecil.DefaultAssemblyResolver.Resolve (Mono.Cecil.AssemblyNameReference name)
Mono.Cecil.MetadataResolver.Resolve (Mono.Cecil.TypeReference type)
Mono.Cecil.ModuleDefinition.Resolve (Mono.Cecil.TypeReference type)
Mono.Cecil.TypeReference.Resolve ()
Mono.Cecil.Mixin.CheckedResolve (Mono.Cecil.TypeReference self)
Mono.Cecil.SignatureReader.ReadCustomAttributeEnum (Mono.Cecil.TypeReference enum_type)
Mono.Cecil.SignatureReader.ReadCustomAttributeElementValue (Mono.Cecil.TypeReference type)
Mono.Cecil.SignatureReader.ReadCustomAttributeElement (Mono.Cecil.TypeReference type)
Mono.Cecil.SignatureReader.ReadCustomAttributeFixedArgument (Mono.Cecil.TypeReference type)
Mono.Cecil.SignatureReader.ReadCustomAttributeNamedArgument (Mono.Collections.Generic.Collection`1& fields, Mono.Collections.Generic.Collection`1& properties)
Mono.Cecil.SignatureReader.ReadCustomAttributeNamedArguments (UInt16 count, Mono.Collections.Generic.Collection`1& fields, Mono.Collections.Generic.Collection`1& properties)
Mono.Cecil.MetadataReader.ReadCustomAttributeSignature (Mono.Cecil.CustomAttribute attribute)
Mono.Cecil.CustomAttribute.<Resolve>b__2 (Mono.Cecil.CustomAttribute attribute, Mono.Cecil.MetadataReader reader)
Mono.Cecil.ModuleDefinition.Read[CustomAttribute,CustomAttribute] (Mono.Cecil.CustomAttribute item, System.Func`3 read)
Mono.Cecil.CustomAttribute.Resolve ()
Mono.Cecil.CustomAttribute.get_ConstructorArguments ()
Mono.Cecil.ImmediateModuleReader.ReadCustomAttributes (ICustomAttributeProvider provider)
Mono.Cecil.ImmediateModuleReader.ReadType (Mono.Cecil.TypeDefinition type)
Mono.Cecil.ImmediateModuleReader.ReadTypes (Mono.Collections.Generic.Collection`1 types)
Mono.Cecil.ImmediateModuleReader.ReadModule (Mono.Cecil.ModuleDefinition module)
Mono.Cecil.ImmediateModuleReader.<ReadModule>b__0 (Mono.Cecil.ModuleDefinition module, Mono.Cecil.MetadataReader reader)
Mono.Cecil.ModuleDefinition.Read[ModuleDefinition,ModuleDefinition] (Mono.Cecil.ModuleDefinition item, System.Func`3 read)
Mono.Cecil.ImmediateModuleReader.ReadModule ()
Mono.Cecil.ModuleReader.CreateModuleFrom (Mono.Cecil.PE.Image image, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.ModuleDefinition.ReadModule (System.IO.Stream stream, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName, Mono.Cecil.ReaderParameters parameters)
Mono.Cecil.AssemblyDefinition.ReadAssembly (System.String fileName, Mono.Cecil.ReaderParameters parameters)
UnityEditor.EditorTestsRunner.GuiHelper.GetSequencePointOfTest (UnityEditor.EditorTestsRunner.EditorTestResult test) (at /Users/builduser/buildslave/unity/build/Extensions/EditorTestsRunner/UnityEditor.EditorTestsRunner/TestRunner/GuiHelper.cs:104)
UnityEditor.EditorTestsRunner.GuiHelper.OpenInEditor (UnityEditor.EditorTestsRunner.EditorTestResult test, Boolean openError) (at /Users/builduser/buildslave/unity/build/Extensions/EditorTestsRunner/UnityEditor.EditorTestsRunner/TestRunner/GuiHelper.cs:84)
UnityEditor.EditorTestsRunner.EditorTestsRunnerWindow+<TestContextClick>c__AnonStorey0.<>m__6 (System.Object data) (at /Users/builduser/buildslave/unity/build/Extensions/EditorTestsRunner/UnityEditor.EditorTestsRunner/TestRunner/EditorTestsRunnerWindow.cs:227)
UnityEditor.GenericMenu.CatchMenu (System.Object userData, System.String[] options, Int32 selected) (at /Users/builduser/buildslave/unity/build/artifacts/generated/common/editor/GenericMenuBindings.gen.cs:122)

- Reproduced in Version 5.4.0b18 (cdaae1c8e465), Version 5.3.4f1 (fdbb5133b820)
- Not reproducible in 5.2
- A workaround is to open the tests manually from the Project window