Let the user know if a method has no attribute

Throw a `NotImplementedException` when someone calls a method that we
won't have an implementation for.

InterfaceStubGenerator/GeneratedInterfaceStubTemplate.mustache

@@ -46,8 +46,13 @@ namespace {{Namespace}}
 {{#MethodList}}
         public virtual {{ReturnType}} {{Name}}({{ArgumentListWithTypes}})
         {
+{{#IsRefitMethod}}    
             var arguments = new object[] { {{ArgumentList}} };
             return ({{ReturnType}}) methodImpls["{{Name}}"](Client, arguments);
+{{/IsRefitMethod}}
+{{^IsRefitMethod}}
+            throw new NotImplementedException("Either this method has no Refit HTTP method attribute or you've used something other than a string literal for the 'path' argument.");
+{{/IsRefitMethod}}
         }
 
 {{/MethodList}}

InterfaceStubGenerator/InterfaceStubGenerator.cs

@@ -113,6 +113,7 @@ public ClassTemplateInfo GenerateClassInfoForInterface(InterfaceDeclarationSynta
                         .Select(y => y.Identifier.ValueText)),
                     ArgumentListWithTypes = String.Join(",", x.ParameterList.Parameters
                         .Select(y => String.Format("{0} {1}", y.Type.ToString(), y.Identifier.ValueText))),
+                    IsRefitMethod = HasRefitHttpMethodAttribute(x)
                 })
                 .ToList();
 
@@ -155,6 +156,7 @@ public class MethodTemplateInfo
         public string Name { get; set; }
         public string ArgumentListWithTypes { get; set; }
         public string ArgumentList { get; set; }
+        public bool IsRefitMethod { get; set; }
     }
 
     public class TemplateInformation

Refit-Tests/InterfaceStubGenerator.cs

@@ -97,7 +97,7 @@ public void GenerateTemplateInfoForInterfaceListSmokeTest()
                 .ToList();
 
             var result = fixture.GenerateTemplateInfoForInterfaceList(input);
-            Assert.AreEqual(3, result.ClassList.Count);
+            Assert.AreEqual(4, result.ClassList.Count);
         }
 
         [Test]

Refit-Tests/RefitStubs.cs

@@ -129,8 +129,7 @@ public virtual Task AnotherRefitMethod()
 
         public virtual Task NoConstantsAllowed()
         {
-            var arguments = new object[] {  };
-            return (Task) methodImpls["NoConstantsAllowed"](Client, arguments);
+            throw new NotImplementedException("Either this method has no Refit HTTP method attribute or you've used something other than a string literal for the 'path' argument.");
         }
 
     }
@@ -211,4 +210,34 @@ public virtual Task Post()
     }
 }
 
+namespace Refit.Tests
+{
+    using RefitInternalGenerated;
+
+    [Preserve]
+    public partial class AutoGeneratedIAmHalfRefit : IAmHalfRefit
+    {
+        public HttpClient Client { get; protected set; }
+        readonly Dictionary<string, Func<HttpClient, object[], object>> methodImpls;
+
+        public AutoGeneratedIAmHalfRefit(HttpClient client, IRequestBuilder requestBuilder)
+        {
+            methodImpls = requestBuilder.InterfaceHttpMethods.ToDictionary(k => k, v => requestBuilder.BuildRestResultFuncForMethod(v));
+            Client = client;
+        }
+
+        public virtual Task Post()
+        {
+            var arguments = new object[] {  };
+            return (Task) methodImpls["Post"](Client, arguments);
+        }
+
+        public virtual Task Get()
+        {
+            throw new NotImplementedException("Either this method has no Refit HTTP method attribute or you've used something other than a string literal for the 'path' argument.");
+        }
+
+    }
+}
+
 

Refit-Tests/RestService.cs

@@ -37,6 +37,14 @@ public interface INoRefitHereBuddy
         Task Post();
     }
 
+    public interface IAmHalfRefit
+    {
+        [Post("/anything")]
+        Task Post();
+
+        Task Get();
+    }
+
     [TestFixture]
     public class RestServiceIntegrationTests
     {
@@ -189,5 +197,16 @@ public void NonRefitInterfacesThrowMeaningfulExceptions()
                 StringAssert.StartsWith("INoRefitHereBuddy", exception.Message);
             }
         }
+
+        [Test]
+        public async Task NonRefitMethodsThrowMeaningfulExceptions() 
+        {
+            try {
+                var fixture = RestService.For<IAmHalfRefit>("http://example.com");
+                await fixture.Get();
+            } catch (NotImplementedException exception) {
+                StringAssert.Contains("no Refit HTTP method attribute", exception.Message);
+            }
+        }
     }
 }