* Default ResourcePath behavior is to look next to .cs file

src/Microsoft.Extensions.Localization/ResourceManagerStringLocalizerFactory.cs

@@ -67,7 +67,9 @@ namespace Microsoft.Extensions.Localization
             var typeInfo = resourceSource.GetTypeInfo();
             var assembly = typeInfo.Assembly;
 
-            var baseName = _applicationEnvironment.ApplicationName + "." + _resourcesRelativePath + typeInfo.FullName;
+            var baseName = string.IsNullOrEmpty(_resourcesRelativePath)
+                ? typeInfo.FullName
+                : _applicationEnvironment.ApplicationName + "." + _resourcesRelativePath + typeInfo.FullName;
 
             return _localizerCache.GetOrAdd(baseName, _ =>
                 new ResourceManagerStringLocalizer(

test/LocalizationWebsite/Models/Customer.fr-FR.resx

@@ -118,6 +118,6 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="Hello" xml:space="preserve">
-    <value>Bonjour from Customer in root folder</value>
+    <value>Bonjour from Customer in Models folder</value>
   </data>
 </root>

test/Microsoft.AspNet.Localization.FunctionalTests/LocalizationTest.cs

@@ -77,7 +77,7 @@ namespace Microsoft.AspNet.Localization.FunctionalTests
                 applicationBaseUrl,
                 "ResourcesAtRootFolder",
                 "fr-FR",
-                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in root folder");
+                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in Models folder");
         }
 
         [ConditionalFact]
@@ -92,7 +92,7 @@ namespace Microsoft.AspNet.Localization.FunctionalTests
                 "http://localhost:5076",
                 "ResourcesAtRootFolder",
                 "fr-FR",
-                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in root folder");
+                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in Models folder");
         }
 
         [ConditionalFact]
@@ -107,7 +107,7 @@ namespace Microsoft.AspNet.Localization.FunctionalTests
                 "http://localhost:5077/",
                 "ResourcesAtRootFolder",
                 "fr-FR",
-                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in root folder");
+                "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in Models folder");
         }
     }
 }