1 files changed, 73 insertions, 0 deletions
diff --git a/test/prism/redundant_return_test.rb b/test/prism/redundant_return_test.rb
new file mode 100644
index 0000000000..c668169245
--- /dev/null
+++ b/test/prism/redundant_return_test.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+module Prism
+  class RedundantReturnTest < TestCase
+    def test_statements
+      assert_redundant_return("def foo; return; end")
+      refute_redundant_return("def foo; return; 1; end")
+    end
+
+    def test_begin_implicit
+      assert_redundant_return("def foo; return; rescue; end")
+      refute_redundant_return("def foo; return; 1; rescue; end")
+      refute_redundant_return("def foo; return; rescue; else; end")
+    end
+
+    def test_begin_explicit
+      assert_redundant_return("def foo; begin; return; rescue; end; end")
+      refute_redundant_return("def foo; begin; return; 1; rescue; end; end")
+      refute_redundant_return("def foo; begin; return; rescue; else; end; end")
+    end
+
+    def test_if
+      assert_redundant_return("def foo; return if bar; end")
+    end
+
+    def test_unless
+      assert_redundant_return("def foo; return unless bar; end")
+    end
+
+    def test_else
+      assert_redundant_return("def foo; if bar; baz; else; return; end; end")
+    end
+
+    def test_case_when
+      assert_redundant_return("def foo; case bar; when baz; return; end; end")
+    end
+
+    def test_case_else
+      assert_redundant_return("def foo; case bar; when baz; else; return; end; end")
+    end
+
+    def test_case_match_in
+      assert_redundant_return("def foo; case bar; in baz; return; end; end")
+    end
+
+    def test_case_match_else
+      assert_redundant_return("def foo; case bar; in baz; else; return; end; end")
+    end
+
+    private
+
+    def assert_redundant_return(source)
+      assert find_return(source).redundant?
+    end
+
+    def refute_redundant_return(source)
+      refute find_return(source).redundant?
+    end
+
+    def find_return(source)
+      queue = [Prism.parse(source).value]
+
+      while (current = queue.shift)
+        return current if current.is_a?(ReturnNode)
+        queue.concat(current.compact_child_nodes)
+      end
+
+      flunk "Could not find return node in #{node.inspect}"
+    end
+  end
+end