Add a testcase for deterministic msgid order

tests/roots/test-intl-template/_templates/template1.html

@@ -0,0 +1,5 @@
+{% extends "layout.html" %}
+{% block body %}
+  <h1>{{ _('Template 1') }}</h1>
+  <p>{%trans%}This is Template 1.{%endtrans%}</p>
+{% endblock %}

tests/roots/test-intl-template/_templates/template2.html

@@ -0,0 +1,5 @@
+{% extends "layout.html" %}
+{% block body %}
+  <h1>{{ _('Template 2') }}</h1>
+  <p>{%trans%}This is Template 2.{%endtrans%}</p>
+{% endblock %}

tests/roots/test-intl-template/conf.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+templates_path = ['_templates']

tests/test_build_gettext.py

@@ -165,3 +165,18 @@ def test_gettext_template(app):
     result = (app.outdir / 'sphinx.pot').text(encoding='utf-8')
     assert "Welcome" in result
     assert "Sphinx %(version)s" in result
+
+
+@pytest.mark.sphinx('gettext', testroot='intl-template')
+def test_gettext_template_msgid_order_in_sphinxpot(app):
+    app.builder.build_all()
+    assert (app.outdir / 'sphinx.pot').isfile()
+
+    result = (app.outdir / 'sphinx.pot').text(encoding='utf-8')
+    assert re.search(
+        ('msgid "Template 1".*'
+         'msgid "This is Template 1\.".*'
+         'msgid "Template 2".*'
+         'msgid "This is Template 2\.".*'),
+        result,
+        flags=re.S)