Only create fresh environment for a MethodAddBlock block

The call part of a MethodAddBlock node occurs in the same environment.
Only the block portion of it occurs in a fresh environment.

Author: vinistock

lib/syntax_tree/visitor/with_environment.rb

@@ -44,8 +44,12 @@ def visit_module(node)
       with_new_environment { super }
     end
 
+    # When we find a method invocation with a block, only the code that happens
+    # inside of the block needs a fresh environment. The method invocation
+    # itself happens in the same environment
     def visit_method_add_block(node)
-      with_new_environment { super }
+      visit(node.call)
+      with_new_environment { visit(node.block) }
     end
 
     def visit_def(node)

test/visitor_with_environment_test.rb

@@ -506,5 +506,32 @@ def test_aref_on_a_method_call_with_arguments
       assert_equal(1, variable.definitions[0].start_line)
       assert_equal(2, variable.usages[0].start_line)
     end
+
+    def test_double_aref_on_method_call
+      tree = SyntaxTree.parse(<<~RUBY)
+        object = MyObject.new
+        object["attributes"].find { |a| a["field"] == "expected" }["value"] = "changed"
+      RUBY
+
+      visitor = Collector.new
+      visitor.visit(tree)
+
+      assert_equal(1, visitor.arguments.length)
+      assert_equal(1, visitor.variables.length)
+
+      variable = visitor.variables["object"]
+      assert_equal(1, variable.definitions.length)
+      assert_equal(1, variable.usages.length)
+
+      assert_equal(1, variable.definitions[0].start_line)
+      assert_equal(2, variable.usages[0].start_line)
+
+      argument = visitor.arguments["a"]
+      assert_equal(1, argument.definitions.length)
+      assert_equal(1, argument.usages.length)
+
+      assert_equal(2, argument.definitions[0].start_line)
+      assert_equal(2, argument.usages[0].start_line)
+    end
   end
 end