test: Add test for method mixins.

Author: varungandhi-src

test/scip/testdata/mixin.rb

@@ -0,0 +1,40 @@
+# typed: true
+
+module M
+  def f
+    puts 'M.f'
+  end
+end
+
+class C1
+  include M
+  def f
+    puts 'C1.f'
+  end
+end
+
+# f refers to C1.f
+class C2 < C1
+end
+
+# f refers to C1.f
+class C3 < C1
+  include M
+end
+
+class D1
+  def f
+    puts 'D1.f'
+  end
+end
+
+class D2
+  include M
+end
+
+C1.new.f # C1.f
+C2.new.f # C1.f
+C3.new.f # C1.f
+
+D1.new.f # D1.f
+D2.new.f # M.f

test/scip/testdata/mixin.snapshot.rb

@@ -0,0 +1,74 @@
+ # typed: true
+ 
+ module M
+#       ^ definition [..] M#
+   def f
+#      ^ definition [..] M#f().
+     puts 'M.f'
+   end
+ end
+ 
+ class C1
+#      ^^ definition [..] C1#
+   include M
+#  ^^^^^^^ reference [..] Module#include().
+#          ^ reference [..] M#
+   def f
+#      ^ definition [..] C1#f().
+     puts 'C1.f'
+#    ^^^^ reference [..] Kernel#puts().
+   end
+ end
+ 
+ # f refers to C1.f
+ class C2 < C1
+#      ^^ definition [..] C2#
+#           ^^ definition [..] C1#
+ end
+ 
+ # f refers to C1.f
+ class C3 < C1
+#      ^^ definition [..] C3#
+#           ^^ definition [..] C1#
+   include M
+#  ^^^^^^^ reference [..] Module#include().
+#          ^ reference [..] M#
+ end
+ 
+ class D1
+#      ^^ definition [..] D1#
+   def f
+#      ^ definition [..] D1#f().
+     puts 'D1.f'
+#    ^^^^ reference [..] Kernel#puts().
+   end
+ end
+ 
+ class D2
+#      ^^ definition [..] D2#
+   include M
+#  ^^^^^^^ reference [..] Module#include().
+#          ^ reference [..] M#
+ end
+ 
+ C1.new.f # C1.f
+#^^ reference [..] C1#
+#   ^^^ reference [..] Class#new().
+#       ^ reference [..] C1#f().
+ C2.new.f # C1.f
+#^^ reference [..] C2#
+#   ^^^ reference [..] Class#new().
+#       ^ reference [..] C1#f().
+ C3.new.f # C1.f
+#^^ reference [..] C3#
+#   ^^^ reference [..] Class#new().
+#       ^ reference [..] C1#f().
+ 
+ D1.new.f # D1.f
+#^^ reference [..] D1#
+#   ^^^ reference [..] Class#new().
+#       ^ reference [..] D1#f().
+ D2.new.f # M.f
+#^^ reference [..] D2#
+#   ^^^ reference [..] Class#new().
+#       ^ reference [..] M#f().