reorganize css tests (part 2) (#3227)

**What problem is this PR intended to solve?**

As part of the preparation for overhauling the CSS parser, doing some
cleanup in the CSS tests to make them easier to understand and easier to
instrument.

lib/nokogiri/css/selector_cache.rb

@@ -22,7 +22,7 @@ def []=(key, value)
         # Clear the cache
         def clear_cache(create_new_object = false)
           @mutex.synchronize do
-            if create_new_object
+            if create_new_object # used in tests to avoid 'method redefined' warnings when injecting spies
               @cache = {}
             else
               @cache.clear

test/css/test_css.rb

@@ -69,6 +69,12 @@
         assert_raises(TypeError) { Nokogiri::CSS.xpath_for(Object.new) }
         assert_raises(TypeError) { Nokogiri::CSS.xpath_for(["foo", "bar"]) }
       end
+
+      it "raises an exception for pseudo-classes that are not XPath Names" do
+        # see https://github.com/sparklemotion/nokogiri/issues/3193
+        assert_raises(Nokogiri::CSS::SyntaxError) { Nokogiri::CSS.xpath_for("div:-moz-drag-over") }
+        assert_raises(Nokogiri::CSS::SyntaxError) { Nokogiri::CSS.xpath_for("div:-moz-drag-over()") }
+      end
     end
   end
 end

test/css/test_selector_cache.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+require "helper"
+
+describe Nokogiri::CSS::SelectorCache do
+  before do
+    Nokogiri::CSS::SelectorCache.clear_cache
+    Nokogiri::CSS::SelectorCache.class_eval do
+      class << @cache
+        alias_method :old_bracket, :[]
+
+        def access_count
+          @access_count ||= 0
+        end
+
+        def [](key)
+          @access_count ||= 0
+          @access_count += 1
+          old_bracket(key)
+        end
+      end
+    end
+  end
+
+  after do
+    Nokogiri::CSS::SelectorCache.clear_cache(true)
+  end
+
+  let(:selector_list) { "a1 > b2 > c3" }
+
+  it "uses the cache by default" do
+    Nokogiri::CSS.xpath_for(selector_list)
+    Nokogiri::CSS.xpath_for(selector_list)
+
+    assert_equal(1, Nokogiri::CSS::SelectorCache.class_eval { @cache.count })
+    assert_equal(2, Nokogiri::CSS::SelectorCache.class_eval { @cache.access_count })
+  end
+
+  it "uses the cache when explicitly requested" do
+    Nokogiri::CSS.xpath_for(selector_list, cache: true)
+    Nokogiri::CSS.xpath_for(selector_list, cache: true)
+
+    assert_equal(1, Nokogiri::CSS::SelectorCache.class_eval { @cache.count })
+    assert_equal(2, Nokogiri::CSS::SelectorCache.class_eval { @cache.access_count })
+  end
+
+  it "does not use the cache when explicitly requested" do
+    Nokogiri::CSS.xpath_for(selector_list, cache: false)
+    Nokogiri::CSS.xpath_for(selector_list, cache: false)
+
+    assert_equal(0, Nokogiri::CSS::SelectorCache.class_eval { @cache.count })
+    assert_equal(0, Nokogiri::CSS::SelectorCache.class_eval { @cache.access_count })
+  end
+
+  it "uses the cached expressions" do
+    Nokogiri::CSS::SelectorCache.clear_cache
+
+    cache = Nokogiri::CSS::SelectorCache.instance_variable_get(:@cache)
+
+    assert_empty(cache)
+    Nokogiri::CSS.xpath_for(selector_list)
+    refute_empty(cache)
+    key = cache.keys.first
+
+    cache[key] = ["this is an injected value"]
+    assert_equal(["this is an injected value"], Nokogiri::CSS.xpath_for(selector_list))
+  end
+
+  it "test_cache_key_on_ns_prefix_and_visitor_config" do
+    Nokogiri::CSS::SelectorCache.clear_cache
+
+    cache = Nokogiri::CSS::SelectorCache.instance_variable_get(:@cache)
+    assert_empty(cache)
+
+    Nokogiri::CSS.xpath_for(selector_list)
+    Nokogiri::CSS.xpath_for(selector_list, prefix: ".//")
+    Nokogiri::CSS.xpath_for(selector_list, prefix: ".//", ns: { "example" => "http://example.com/" })
+    Nokogiri::CSS.xpath_for(
+      selector_list,
+      visitor: Nokogiri::CSS::XPathVisitor.new(
+        builtins: Nokogiri::CSS::XPathVisitor::BuiltinsConfig::ALWAYS,
+        prefix: ".//",
+        namespaces: { "example" => "http://example.com/" },
+      ),
+    )
+    Nokogiri::CSS.xpath_for(
+      selector_list,
+      visitor: Nokogiri::CSS::XPathVisitor.new(
+        builtins: Nokogiri::CSS::XPathVisitor::BuiltinsConfig::ALWAYS,
+        doctype: Nokogiri::CSS::XPathVisitor::DoctypeConfig::HTML5,
+        prefix: ".//",
+        namespaces: { "example" => "http://example.com/" },
+      ),
+    )
+    assert_equal(5, cache.length)
+  end
+end