lint: discourage NoSuchElementError, fixes SD-1770

test plan:
* see test commit

Change-Id: Iab77491cdacf65249a8edd732617d7c771c0c78e
Reviewed-on: https://gerrit.instructure.com/97276
Tested-by: Jenkins
Reviewed-by: Shawn Meredith <shawn@instructure.com>
Product-Review: Shawn Meredith <shawn@instructure.com>
QA-Review: Shawn Meredith <shawn@instructure.com>

Author: Landon Wilkins

gems/rubocop-canvas/config/default.yml

@@ -70,6 +70,9 @@ Specs/NoExecuteScript:
   Exclude:
     - "**/spec/selenium/test_setup/**/*.rb"
 
+Specs/NoNoSuchElementError:
+  <<: *Specs
+
 Specs/NoStrftime:
   <<: *Specs
 

gems/rubocop-canvas/lib/rubocop_canvas.rb

@@ -28,6 +28,7 @@
 require 'rubocop_canvas/cops/specs/no_before_once_stubs'
 require 'rubocop_canvas/cops/specs/ensure_spec_extension'
 require 'rubocop_canvas/cops/specs/no_execute_script'
+require 'rubocop_canvas/cops/specs/no_no_such_element_error'
 require 'rubocop_canvas/cops/specs/no_strftime'
 require 'rubocop_canvas/cops/specs/prefer_f_over_fj'
 require 'rubocop_canvas/cops/specs/scope_helper_modules'

gems/rubocop-canvas/lib/rubocop_canvas/cops/specs/no_no_such_element_error.rb

@@ -0,0 +1,36 @@
+module RuboCop
+  module Cop
+    module Specs
+      class NoNoSuchElementError < Cop
+        MSG = "Avoid using Selenium::WebDriver::Error::NoSuchElementError.\n" \
+              "Our finders (f/fj and ff/ffj) will wait up to the implicit wait" \
+              " (just like find_element, etc), and will raise a" \
+              " Selenium::WebDriver::Error::NoSuchElementError" \
+              " (just like find_element, etc).\n" \
+              "Look through custom_selenium_rspec_matchers.rb, particularly" \
+              " contain_css and contain_jqcss."
+
+        BAD_CONST = "Selenium::WebDriver::Error::NoSuchElementError"
+        BAD_CONST_MATCHER = BAD_CONST.split("::")
+                              .map { |name| ":#{name})" }
+                              .join(" ")
+
+        # (const
+        #   (const
+        #     (const
+        #       (const nil :Selenium) :WebDriver) :Error) :NoSuchElementError)
+        def_node_matcher :bad_const?, <<-PATTERN
+          (const
+            (const
+              (const
+                (const nil #{BAD_CONST_MATCHER}
+        PATTERN
+
+        def on_const(node)
+          return unless bad_const?(node)
+          add_offense node, :expression, MSG, :warning
+        end
+      end
+    end
+  end
+end

gems/rubocop-canvas/spec/rubocop/cop/specs/no_no_such_element_error_spec.rb

@@ -0,0 +1,44 @@
+describe RuboCop::Cop::Specs::NoNoSuchElementError do
+  subject(:cop) { described_class.new }
+  let(:msg_regex) { /Avoid using Selenium::WebDriver::Error::NoSuchElementError/ }
+
+  it 'disallows Selenium::WebDriver::Error::NoSuchElementError' do
+    inspect_source(cop, %{
+      describe "breaks all the things" do
+        it 'is a bad spec' do
+          Selenium::WebDriver::Error::NoSuchElementError
+        end
+      end
+    })
+    expect(cop.offenses.size).to eq(1)
+    expect(cop.messages.first).to match(msg_regex)
+    expect(cop.offenses.first.severity.name).to eq(:warning)
+  end
+
+  it 'disallows rescuing Selenium::WebDriver::Error::NoSuchElementError' do
+    inspect_source(cop, %{
+      def not_found?
+        find("#yar")
+        false
+      rescue Selenium::WebDriver::Error::NoSuchElementError
+        true
+      end
+    })
+    expect(cop.offenses.size).to eq(1)
+    expect(cop.messages.first).to match(msg_regex)
+    expect(cop.offenses.first.severity.name).to eq(:warning)
+  end
+
+  it 'disallows raising Selenium::WebDriver::Error::NoSuchElementError' do
+    inspect_source(cop, %{
+      def not_found?
+        a = find("#yar")
+        return true if a
+        raise Selenium::WebDriver::Error::NoSuchElementError
+      end
+    })
+    expect(cop.offenses.size).to eq(1)
+    expect(cop.messages.first).to match(msg_regex)
+    expect(cop.offenses.first.severity.name).to eq(:warning)
+  end
+end