Fix liniting errors

src/registrar/config/urls.py

@@ -63,6 +63,11 @@ urlpatterns = [
     ),
     path("domain/<int:pk>", views.DomainView.as_view(), name="domain"),
     path("domain/<int:pk>/users", views.DomainUsersView.as_view(), name="domain-users"),
+    path(
+        "domain/<int:pk>/users/add",
+        views.DomainAddUserView.as_view(),
+        name="domain-users-add",
+    ),
 ]
 
 

src/registrar/fixtures.py

@@ -254,6 +254,7 @@ class DomainApplicationFixture:
                 except Exception as e:
                     logger.warning(e)
 
+
 class DomainFixture(DomainApplicationFixture):
 
     """Create one domain and permissions on it for each user."""
@@ -268,7 +269,9 @@ class DomainFixture(DomainApplicationFixture):
 
         for user in users:
             # approve one of each users investigating status domains
-            application = DomainApplication.objects.filter(creator=user, status=DomainApplication.INVESTIGATING).last()
+            application = DomainApplication.objects.filter(
+                creator=user, status=DomainApplication.INVESTIGATING
+            ).last()
             logger.debug(f"Approving {application} for {user}")
             application.approve()
             application.save()

src/registrar/templates/domain_add_user.html

@@ -0,0 +1,24 @@
+{% extends "domain_base.html" %}
+{% load static field_helpers %}
+
+{% block title %}Add another user{% endblock %}
+
+{% block domain_content %}
+  <h1>Add another user</h1>
+
+  <p>You can add another user to help manage your domain. They will need to sign
+  into the .gov registrar with their Login.gov account.
+  </p>
+
+  <form class="usa-form usa-form--large" method="post" novalidate>
+    {% csrf_token %}
+
+    {% input_with_errors form.email %}
+
+    <button
+      type="submit"
+      class="usa-button"
+    >Add user</button>
+  </form>
+
+{% endblock %}  {# domain_content #}

src/registrar/templates/domain_sidebar.html

@@ -51,7 +51,7 @@
       <li class="usa-sidenav__item">
         {% url 'domain-users' pk=domain.id as url %}
         <a href="{{ url }}"
-          {% if request.path == url %}class="usa-current"{% endif %}
+          {% if request.path|startswith:url %}class="usa-current"{% endif %}
         >
             User management
         </a>

src/registrar/templates/domain_users.html

@@ -1,4 +1,5 @@
 {% extends "domain_base.html" %}
+{% load static %}
 
 {% block title %}User management{% endblock %}
 
@@ -30,4 +31,11 @@
       aria-live="polite"
     ></div>
   {% endif %}
+
+  <a class="usa-button usa-button--unstyled" href="{% url 'domain-users-add' pk=domain.id %}">
+    <svg class="usa-icon" aria-hidden="true" focusable="false" role="img" width="24" height="24">
+      <use xlink:href="{%static 'img/sprite.svg'%}#add_circle"></use>
+    </svg><span class="margin-left-05">Add another user</span>
+  </a>
+
 {% endblock %}  {# domain_content #}

src/registrar/templatetags/url_helpers.py

@@ -8,3 +8,10 @@ register = template.Library()
 def namespaced_url(namespace, name="", **kwargs):
     """Get a URL, given its Django namespace and name."""
     return reverse(f"{namespace}:{name}", kwargs=kwargs)
+
+
+@register.filter("startswith")
+def startswith(text, starts):
+    if isinstance(text, str):
+        return text.startswith(starts)
+    return False

src/registrar/views/__init__.py

@@ -1,5 +1,5 @@
 from .application import *
-from .domain import *
+from .domain import DomainView, DomainUsersView, DomainAddUserView
 from .health import *
 from .index import *
 from .whoami import *

src/registrar/views/domain.py

@@ -1,8 +1,13 @@
 """View for a single Domain."""
 
+from django import forms
+from django.db import IntegrityError
+from django.shortcuts import redirect
+from django.urls import reverse
 from django.views.generic import DetailView
+from django.views.generic.edit import FormMixin
 
-from registrar.models import Domain
+from registrar.models import Domain, User, UserDomainRole
 
 from .utility import DomainPermission
 
@@ -17,3 +22,53 @@ class DomainUsersView(DomainPermission, DetailView):
     model = Domain
     template_name = "domain_users.html"
     context_object_name = "domain"
+
+
+class DomainAddUserForm(DomainPermission, forms.Form):
+
+    """Form for adding a user to a domain."""
+
+    email = forms.EmailField(label="Email")
+
+    def clean_email(self):
+        requested_email = self.cleaned_data["email"]
+        try:
+            User.objects.get(email=requested_email)
+        except User.DoesNotExist:
+            # TODO: send an invitation email to a non-existent user
+            raise forms.ValidationError("That user does not exist in this system.")
+        return requested_email
+
+
+class DomainAddUserView(DomainPermission, FormMixin, DetailView):
+    template_name = "domain_add_user.html"
+    model = Domain
+    form_class = DomainAddUserForm
+
+    def get_success_url(self):
+        return reverse("domain-users", kwargs={"pk": self.object.pk})
+
+    def post(self, request, *args, **kwargs):
+        self.object = self.get_object()
+        form = self.get_form()
+        if form.is_valid():
+            return self.form_valid(form)
+        else:
+            return self.form_invalid(form)
+
+    def form_valid(self, form):
+        """Add the specified user on this domain."""
+        requested_email = form.cleaned_data["email"]
+        # look up a user with that email
+        # they should exist because we checked in clean_email
+        requested_user = User.objects.get(email=requested_email)
+
+        try:
+            UserDomainRole.objects.create(
+                user=requested_user, domain=self.object, role=UserDomainRole.Roles.ADMIN
+            )
+        except IntegrityError:
+            # User already has the desired role! Do nothing??
+            pass
+
+        return redirect(self.get_success_url())