Add negative scenario

Author: aguspe

rb/spec/integration/selenium/webdriver/bidi/network_spec.rb

@@ -171,7 +171,9 @@ class BiDi
             end
 
             driver.navigate.to url_for('formPage.html')
-            expect(driver.page_source).to include('Hello World!')
+            source = driver.page_source
+            expect(source).not_to include('There should be a form here:')
+            expect(source).to include('Hello World!')
           end
         end
       end

rb/spec/integration/selenium/webdriver/network_spec.rb

@@ -272,7 +272,9 @@ module WebDriver
             response.provide_response
           end
           driver.navigate.to url_for('formPage.html')
-          expect(driver.page_source).to include('Hello World!')
+          source = driver.page_source
+          expect(source).not_to include('There should be a form here:')
+          expect(source).to include('Hello World!')
         end
       end