3 files changed, 115 insertions, 0 deletions
diff --git a/ci/custom_cops/lib/custom_cops.rb b/ci/custom_cops/lib/custom_cops.rb
new file mode 100644
index 0000000000..157b8247e4
--- /dev/null
+++ b/ci/custom_cops/lib/custom_cops.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+require_relative "custom_cops/refute_not"
+require_relative "custom_cops/assert_not"
diff --git a/ci/custom_cops/lib/custom_cops/assert_not.rb b/ci/custom_cops/lib/custom_cops/assert_not.rb
new file mode 100644
index 0000000000..8b49d3eac2
--- /dev/null
+++ b/ci/custom_cops/lib/custom_cops/assert_not.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module CustomCops
+  # Enforces the use of `assert_not` over `assert !`.
+  #
+  # @example
+  #   # bad
+  #   assert !x
+  #   assert ! x
+  #
+  #   # good
+  #   assert_not x
+  #
+  class AssertNot < RuboCop::Cop::Cop
+    MSG = "Prefer `assert_not` over `assert !`"
+
+    def_node_matcher :offensive?, "(send nil? :assert (send ... :!) ...)"
+
+    def on_send(node)
+      add_offense(node) if offensive?(node)
+    end
+
+    def autocorrect(node)
+      expression = node.loc.expression
+
+      ->(corrector) do
+        corrector.replace(
+          expression,
+          corrected_source(expression.source)
+        )
+      end
+    end
+
+    private
+
+      def corrected_source(source)
+        source.gsub(/^assert(\(| ) *! */, "assert_not\\1")
+      end
+  end
+end
diff --git a/ci/custom_cops/lib/custom_cops/refute_not.rb b/ci/custom_cops/lib/custom_cops/refute_not.rb
new file mode 100644
index 0000000000..3e89e0fd32
--- /dev/null
+++ b/ci/custom_cops/lib/custom_cops/refute_not.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module CustomCops
+  # Enforces the use of `#assert_not` methods over `#refute` methods.
+  #
+  # @example
+  #   # bad
+  #   refute false
+  #   refute_empty [1, 2, 3]
+  #   refute_equal true, false
+  #
+  #   # good
+  #   assert_not false
+  #   assert_not_empty [1, 2, 3]
+  #   assert_not_equal true, false
+  #
+  class RefuteNot < RuboCop::Cop::Cop
+    MSG = "Prefer `%<assert_method>s` over `%<refute_method>s`"
+
+    CORRECTIONS = {
+      refute:             "assert_not",
+      refute_empty:       "assert_not_empty",
+      refute_equal:       "assert_not_equal",
+      refute_in_delta:    "assert_not_in_delta",
+      refute_in_epsilon:  "assert_not_in_epsilon",
+      refute_includes:    "assert_not_includes",
+      refute_instance_of: "assert_not_instance_of",
+      refute_kind_of:     "assert_not_kind_of",
+      refute_nil:         "assert_not_nil",
+      refute_operator:    "assert_not_operator",
+      refute_predicate:   "assert_not_predicate",
+      refute_respond_to:  "assert_not_respond_to",
+      refute_same:        "assert_not_same",
+      refute_match:       "assert_no_match"
+    }.freeze
+
+    OFFENSIVE_METHODS = CORRECTIONS.keys.freeze
+
+    def_node_matcher :offensive?, "(send nil? #offensive_method? ...)"
+
+    def on_send(node)
+      return unless offensive?(node)
+
+      message = offense_message(node.method_name)
+      add_offense(node, location: :selector, message: message)
+    end
+
+    def autocorrect(node)
+      ->(corrector) do
+        corrector.replace(
+          node.loc.selector,
+          CORRECTIONS[node.method_name]
+        )
+      end
+    end
+
+    private
+
+      def offensive_method?(method_name)
+        OFFENSIVE_METHODS.include?(method_name)
+      end
+
+      def offense_message(method_name)
+        format(
+          MSG,
+          refute_method: method_name,
+          assert_method: CORRECTIONS[method_name]
+        )
+      end
+  end
+end