Add a unit test for new template tag

src/docker-compose.yml

@@ -28,7 +28,7 @@ services:
       # Tell Django where it is being hosted
       - DJANGO_BASE_URL=http://localhost:8080
       # Public site URL link
-      - GETGOV_PUBLIC_SITE_URL="https://beta.get.gov"
+      - GETGOV_PUBLIC_SITE_URL=https://beta.get.gov
       # Set a username for accessing the registry
       - REGISTRY_CL_ID=nothing
       # Set a password for accessing the registry

src/registrar/templatetags/url_helpers.py

@@ -29,5 +29,9 @@ def public_site_url(url_path):
     variable.
     """
     base_url = settings.GETGOV_PUBLIC_SITE_URL
-    public_url = urljoin(base_url, url_path)
+    # join the two halves with a single slash
+    public_url ="/".join([
+        base_url.rstrip("/"),
+        url_path.lstrip("/")
+    ])
     return public_url

src/registrar/tests/test_templatetags.py

@@ -0,0 +1,31 @@
+"""Test template tags."""
+
+from django.conf import settings
+from django.test import TestCase
+from django.template import Context, Template
+
+class TestTemplateTags(TestCase):
+
+    def _render_template(self, string, context=None):
+        """Helper method to render a template given as a string.
+
+        Originally from https://stackoverflow.com/a/1690879
+        """
+        context = context or {}
+        context = Context(context)
+        return Template(string).render(context)
+
+    def test_public_site_url(self):
+        result = self._render_template(
+            "{% load url_helpers %}{% public_site_url 'directory/page' %}"
+        )
+        self.assertTrue(result.startswith(settings.GETGOV_PUBLIC_SITE_URL))
+        self.assertTrue(result.endswith("/directory/page"))
+
+    def test_public_site_url_leading_slash(self):
+        result = self._render_template(
+            "{% load url_helpers %}{% public_site_url '/directory/page' %}"
+        )
+        self.assertTrue(result.startswith(settings.GETGOV_PUBLIC_SITE_URL))
+        # slash-slash host slash directory slash page
+        self.assertEqual(result.count("/"), 4)