Cosmetic tweaks for evaluate_on_new_document

Author: route

README.md

@@ -124,6 +124,7 @@ browser.mouse
 browser.quit
 ```
 
+
 ## Docker
 
 In docker as root you must pass the no-sandbox browser option:
@@ -739,6 +740,20 @@ simple value.
 browser.execute(%(1 + 1)) # => true
 ```
 
+#### evaluate_on_new_document(expression)
+
+Evaluate JavaScript to modify things before a page load
+
+* expression `String` should be valid JavaScript
+
+```ruby
+browser.evaluate_on_new_document <<~JS
+  Object.defineProperty(navigator, "languages", {
+    get: function() { return ["tlh"]; }
+  });
+JS
+```
+
 #### add_script_tag(\*\*options) : `Boolean`
 
 * options `Hash`
@@ -774,18 +789,6 @@ browser.add_script_tag(content: "window.__injected = 42")
 browser.evaluate("window.__injected") # => 42
 ```
 
-#### evaluate_on_new_document(javascript)
-
-Evaluate JavaScript to modify things before a page load:
-
-```ruby
-javascript = <<~JS
-    Object.defineProperty(navigator, 'languages', {
-      get: function() { return ['tlh']; }
-    });
-  JS
-browser.evaluate_on_new_document javascript
-```
 
 ## Frames
 

lib/ferrum/browser.rb

@@ -77,8 +77,8 @@ def extensions
       end
     end
 
-    def evaluate_on_new_document(javascript)
-      extensions << javascript
+    def evaluate_on_new_document(expression)
+      extensions << expression
     end
 
     def timeout

spec/browser_spec.rb

@@ -206,20 +206,19 @@ module Ferrum
         end
       end
 
-      it 'supports user Javascript' do
+      it "supports evaluation of JavaScript before page loads" do
         begin
-          javascript = <<~JS
-            Object.defineProperty(navigator, 'languages', {
-              get: function() { return ['tlh']; }
+          browser = Browser.new(base_url: base_url)
+
+          browser.evaluate_on_new_document <<~JS
+            Object.defineProperty(navigator, "languages", {
+              get: function() { return ["tlh"]; }
             });
           JS
 
-          browser = Browser.new.tap { |b| b.evaluate_on_new_document(javascript) }
-          browser.go_to(base_url('/ferrum/with_user_js'))
-
-          browser_language = browser.evaluate('document.getElementById("browser-languages").innerHTML')
-
-          expect(browser_language).to eq('tlh')
+          browser.go_to("/ferrum/with_user_js")
+          language = browser.at_xpath("//*[@id='browser-languages']/text()").text
+          expect(language).to eq("tlh")
         ensure
           browser&.quit
         end