Fix an issue with generic methods whose only generic type is the return

The return type was not being used to index into the Expectations
object. Probably I didn't do that to allow generic methods returning
references, because older versions of Mockall didn't already determine
the owned form of the return type.

Fixes #236

CHANGELOG.md

@@ -49,6 +49,10 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- Fixed setting multiple expectations on generic methods whose only generic
+  type is the return.
+  ([#238](https://github.com/asomers/mockall/pull/238))
+
 - Fixed mocking generic structs with generic methods whose only generic types
   are lifetimes.  This is useful for mocking generic structs that implement
   traits like `Future` and `Stream`.

mockall/tests/mock_generic_return.rs

@@ -12,6 +12,8 @@ mock! {
 #[test]
 fn returning() {
     let mut mock = MockFoo::new();
-    mock.expect_foo::<i32>().return_const(42);
+    mock.expect_foo::<i32>().return_const(42i32);
+    mock.expect_foo::<u16>().return_const(69u16);
     assert_eq!(42i32, mock.foo());
+    assert_eq!(69u16, mock.foo());
 }

mockall_derive/src/mock_function.rs

@@ -1085,11 +1085,12 @@ impl<'a> ToTokens for ExpectationGuardCommonMethods<'a> {
 
         let argnames = &self.f.argnames;
         let argty = &self.f.argty;
+        let oo = &self.f.owned_output;
         let (_, tg, _) = self.f.egenerics.split_for_impl();
         let expectations = if self.f.is_expectation_generic() {
             quote!(self.guard
                    .store
-                   .get_mut(&::mockall::Key::new::<(#(#argty, )*)>())
+                   .get_mut(&::mockall::Key::new::<(#oo, #(#argty, )*)>())
                    .unwrap()
                    .downcast_mut::<Expectations #tg>()
                    .unwrap())
@@ -1326,6 +1327,7 @@ impl<'a> ToTokens for GenericExpectationGuard<'a> {
         egenerics.gt_token.get_or_insert(<Token![>]>::default());
         let (e_ig, e_tg, e_wc) = egenerics.split_for_impl();
         let fn_params = &self.f.fn_params;
+        let oo = &self.f.owned_output;
         let tbf = tg.as_turbofish();
         let v = &self.f.privmod_vis;
         quote!(
@@ -1354,7 +1356,7 @@ impl<'a> ToTokens for GenericExpectationGuard<'a> {
                 {
                     let __mockall_ee: &mut Expectations #tg =
                         __mockall_guard.store.entry(
-                            ::mockall::Key::new::<(#(#argty, )*)>()
+                            ::mockall::Key::new::<(#oo, #(#argty, )*)>()
                         ).or_insert_with(||
                             Box::new(Expectations #tbf ::new()))
                         .downcast_mut()
@@ -2291,6 +2293,7 @@ impl<'a> ToTokens for StaticGenericExpectations<'a> {
             send_syncify(&mut any_wc, self.f.owned_output.clone());
         }
         let tbf = tg.as_turbofish();
+        let oo = &self.f.owned_output;
         let output = &self.f.output;
         let v = &self.f.privmod_vis;
         let (call, get, self_, downcast) = if self.f.return_refmut {
@@ -2311,7 +2314,7 @@ impl<'a> ToTokens for StaticGenericExpectations<'a> {
                 #v fn #call #ig (#self_, #(#argnames: #argty, )* )
                     -> Option<#output> #wc
                 {
-                    self.store.#get(&::mockall::Key::new::<(#(#argty, )*)>())
+                    self.store.#get(&::mockall::Key::new::<(#oo, #(#argty, )*)>())
                         .map(|__mockall_e| {
                             __mockall_e.#downcast::<Expectations #tg>()
                             .unwrap()
@@ -2322,7 +2325,7 @@ impl<'a> ToTokens for StaticGenericExpectations<'a> {
                 /// Create a new Expectation.
                 #v fn expect #ig (&mut self) -> &mut Expectation #tg #any_wc
                 {
-                    self.store.entry(::mockall::Key::new::<(#(#argty, )*)>())
+                    self.store.entry(::mockall::Key::new::<(#oo, #(#argty, )*)>())
                         .or_insert_with(|| Box::new(Expectations #tbf::new()))
                         .downcast_mut::<Expectations #tg>()
                         .unwrap()