This test exercises basic 'stub methods' functionality.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type C int

var _ error = C(0) //@suggestedfix(re"C.0.", re"missing method Error", stub)
-- @stub/a/a.go --
--- before
+++ after
@@ -3 +3,6 @@
-type C int
+type C int
+
+// Error implements error.
+func (C) Error() string {
+	panic("unimplemented")
+}
