Merge pull request #47 from kaspth/readable-regex-errors

Readable regex errors

Author: kaspth

lib/rails/dom/testing/assertions/selector_assertions.rb

@@ -166,13 +166,14 @@ def assert_select(*args, &block)
 
           selector = HTMLSelector.new(args, @selected) { nodeset document_root_element }
 
-          if selecting_no_body?(selector)
+          if selector.selecting_no_body?
             assert true
             return
           end
 
           selector.select.tap do |matches|
-            assert_size_match!(matches.size, selector.tests, selector.selector, selector.message)
+            assert_size_match!(matches.size, selector.tests,
+              selector.css_selector, selector.message)
 
             nest_selection(matches, &block) if block_given? && !matches.empty?
           end
@@ -284,12 +285,6 @@ def assert_size_match!(size, equals, css_selector, message = nil)
             end
           end
 
-          def selecting_no_body?(html_selector)
-            # Nokogiri gives the document a body element. Which means we can't
-            # run an assertion expecting there to not be a body.
-            html_selector.selector == 'body' && html_selector.tests[:count] == 0
-          end
-
           def nest_selection(selection)
             # Set @selected to allow nested assert_select.
             # Can be nested several levels deep.

lib/rails/dom/testing/assertions/selector_assertions/html_selector.rb

@@ -2,12 +2,12 @@
 require_relative 'substitution_context'
 
 class HTMLSelector #:nodoc:
-  attr_reader :selector, :tests, :message
+  attr_reader :css_selector, :tests, :message
 
   def initialize(values, previous_selection = nil, &root_fallback)
     @values = values
     @root = extract_root(previous_selection, root_fallback)
-    @selector = extract_selector
+    extract_selectors
     @tests = extract_equality_tests
     @message = @values.shift
 
@@ -16,8 +16,14 @@ def initialize(values, previous_selection = nil, &root_fallback)
     end
   end
 
+  def selecting_no_body? #:nodoc:
+    # Nokogiri gives the document a body element. Which means we can't
+    # run an assertion expecting there to not be a body.
+    @selector == 'body' && @tests[:count] == 0
+  end
+
   def select
-    filter @root.css(selector, context)
+    filter @root.css(@selector, context)
   end
 
   private
@@ -67,15 +73,15 @@ def extract_root(previous_selection, root_fallback)
     end
   end
 
-  def extract_selector
+  def extract_selectors
     selector = @values.shift
 
     unless selector.is_a? String
       raise ArgumentError, "Expecting a selector as the first argument"
     end
 
-    context.substitute!(selector, @values)
-    selector
+    @css_selector = context.substitute!(selector, @values.dup, true)
+    @selector     = context.substitute!(selector, @values)
   end
 
   def extract_equality_tests

lib/rails/dom/testing/assertions/selector_assertions/substitution_context.rb

@@ -3,18 +3,26 @@ def initialize
     @substitute = '?'
   end
 
-  def substitute!(selector, values)
+  def substitute!(selector, values, format_for_presentation = false)
+    selector = selector.dup
+
     while !values.empty? && substitutable?(values.first) && selector.index(@substitute)
-      selector.sub! @substitute, matcher_for(values.shift)
+      selector.sub! @substitute, matcher_for(values.shift, format_for_presentation)
     end
+
+    selector
   end
 
   def match(matches, attribute, matcher)
     matches.find_all { |node| node[attribute] =~ Regexp.new(matcher) }
   end
 
   private
-    def matcher_for(value)
+    def matcher_for(value, format_for_presentation)
+      if format_for_presentation && value.is_a?(Regexp)
+        value = value.inspect # Inspect Regexps for readability in error messages.
+      end
+
       value.to_s.inspect # Nokogiri doesn't like arbitrary values without quotes, hence inspect.
     end
 

test/selector_assertions_test.rb

@@ -232,6 +232,16 @@ def test_css_select_with_invalid_selector
     end
   end
 
+  def test_nested_assert_select_with_match_failure_shows_nice_regex
+    render_html %Q{<div id="1">foo</div>}
+
+    error = assert_raises Minitest::Assertion do
+      assert_select "div:match('id', ?)", /wups/
+    end
+
+    assert_match %Q{div:match('id', "/wups/")}, error.message
+  end
+
   def test_feed_item_encoded
     render_xml <<-EOF
 <rss version="2.0">