Use myhtml in plugin helper and add tests (#320)

spec/asset/plugins/plugin/info.json

@@ -0,0 +1,6 @@
+{
+	"id": "test",
+	"title": "Test Plugin",
+	"placeholder": "placeholder",
+	"wait_seconds": 1
+}

spec/plugin_spec.cr

@@ -0,0 +1,70 @@
+require "./spec_helper"
+
+describe Plugin do
+  describe "helper functions" do
+    it "mango.text" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.text('<a href="https://github.com">Click Me<a>');
+      JS
+        res.should eq "Click Me"
+      end
+    end
+
+    it "mango.text returns empty string when no text" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.text('<img src="https://github.com" />');
+        JS
+        res.should eq ""
+      end
+    end
+
+    it "mango.css" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.css('<ul><li class="test">A</li><li class="test">B</li><li>C</li></ul>', 'li.test');
+
+        JS
+        res.should eq ["<li class=\"test\">A</li>", "<li class=\"test\">B</li>"]
+      end
+    end
+
+    it "mango.css returns empty array when no match" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.css('<ul><li class="test">A</li><li class="test">B</li><li>C</li></ul>', 'li.noclass');
+        JS
+        res.should eq [] of String
+      end
+    end
+
+    it "mango.attribute" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.attribute('<a href="https://github.com">Click Me<a>', 'href');
+        JS
+        res.should eq "https://github.com"
+      end
+    end
+
+    it "mango.attribute returns undefined when no match" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.attribute('<div />', 'href') === undefined;
+        JS
+        res.should be_true
+      end
+    end
+
+    # https://github.com/hkalexling/Mango/issues/320
+    it "mango.attribute handles tags in attribute values" do
+      with_plugin do |plugin|
+        res = plugin.eval <<-JS
+        mango.attribute('<div data-a="<img />" data-b="test" />', 'data-b');
+        JS
+        res.should eq "test"
+      end
+    end
+  end
+end

spec/spec_helper.cr

@@ -3,6 +3,7 @@ require "../src/queue"
 require "../src/server"
 require "../src/config"
 require "../src/main_fiber"
+require "../src/plugin/plugin"
 
 class State
   @@hash = {} of String => String
@@ -54,3 +55,10 @@ def with_storage
     end
   end
 end
+
+def with_plugin
+  with_default_config do
+    plugin = Plugin.new "test", "spec/asset/plugins"
+    yield plugin
+  end
+end