Adding new language to Gedit

I need to add a new language in Gedit. The problem is, it is included in Gedit menu of languages now, but its syntax is not highlighted and Gedit is not able to indentify the language just from the file suffix.

I’ve created both .lang file and a XML file describing MIME-TYPE.

LANG file - /usr/share/gtksourceview-3.0/language-specs/test.lang
MIME-TYPE file - /usr/share/mime/packages/test.xml

After creating them I’ve updated the mime database.

sudo update-mime-database /usr/share/mime

Next attempts

1) I’ve tried even copying test.xml file to /usr/share/mime/applications folder instead of /usr/share/mime/packages, but it had no effect.

2) I’ve tried to put the mime type into the /etc/mime.types as

text/x-test test

and it had no effect too.

test.lang

<?xml version="1.0" encoding="UTF-8"?>
<language id="test" _name="Test" version="1.0" _section="Source">
    <metadata>
        <property name="mimetypes">text/x-test</property>
        <property name="globs">*.test</property>
        <property name="line-comment-start">//</property>
        <property name="block-comment-start">/*</property>
        <property name="block-comment-end">*/</property>
    </metadata>

    <styles>
       <style id="comment" _name="Comment" map-to="def:comment"/>
       <style id="keyword" _name="Keyword" map-to="def:keyword"/>
    </styles>

    <definitions>
        <context id="if0-comment" style-ref="comment">
          <start>%{preproc-start}ifbs*0b</start>
          <end>%{preproc-start}(endif|else|elif)b</end>
          <include>
            <context id="if-in-if0">
              <start>%{preproc-start}if(n?def)?b</start>
              <end>%{preproc-start}endifb</end>
              <include>
                <context ref="if-in-if0"/>
                <context ref="def:in-comment"/>
              </include>
            </context>
            <context ref="def:in-comment"/>
          </include>
        </context>

        <context id="keywords" style-ref="keyword">
            <keyword>hello</keyword>
            <keyword>hi</keyword>
        </context>

        <!--Main context-->
        <context id="test">
            <include>
                <context ref="if0-comment"/>
                <context ref="keywords"/>
            </include>
        </context>

    </definitions>
</language>

test.xml

<?xml version="1.0" encoding="utf-8"?>
<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info" >
  <mime-type type="text/x-test">
    <sub-class-of type="text/plain"/>
    <comment xml:lang="en">TEST language document</comment>
    <comment xml:lang="cs">Dokument v jazyce TEST</comment>
    <glob pattern="*.test"/>
  </mime-type>
</mime-info>