Merge branch 'py36-migration'

Upgrade the code base to Python 3.6+ and drop support for older Pythons,
in summary:

* Migrate old %-format and str.format to f-strings,
* Take advantage of the os.PathLike interface where possible
* Remove compatibility workarounds (e.g., for the `json` module)

As part of this change I have also refactored all `with` and `except`
blocks.  During that I found and fixed some bogus tests.

Furthermore, I have normalized string literals according to the
algorithm that `repr(…)` uses, i.e., strings are now preferably
surrounded by single quotes.

Please have a look at the individual commit messages for details.

Fixes: #300

.travis.yml

@@ -2,25 +2,6 @@ dist: trusty
 
 matrix:
   include:
-    - language: python
-      name: "Python 3.5 Checks"
-      python:
-        - "3.5"
-      services:
-        - docker
-      cache:
-        pip: true
-      install:
-        - pip install -r build-requirements.txt
-        - pip install codacy-coverage
-        - make
-      script:
-        - make lint
-        - make coverage
-      after_success:
-        - pipenv run coverage xml
-        - python-codacy-coverage
-
     - language: python
       name: "Python 3.6 Checks"
       python:

Pipfile

@@ -24,6 +24,6 @@ coverage = "*"
 "flake8" = "*"
 "flake8-docstrings" = "*"
 isort = "*"
-ipython = "<7.10"
+ipython = "*"
 honcho = "*"
 django-html-validator = "*"

README.md

@@ -33,7 +33,7 @@ application to manage online programming courses, powered by Git, Django and Doc
 INLOOP requires the following software:
 
 * Debian 8+ or Ubuntu 16.04+, macOS 10.11+ (for development only)
-* Python 3.5, 3.6 or 3.7
+* Python 3.6 or 3.7
 * Docker 1.10+ ([Docker setup](docs/docker_setup.md) **!!!**)
 * Redis 2.6+
 * Git 2.3+ ([workarounds for older Git versions](docs/git_troubleshouting.md))

inloop/accounts/admin.py

@@ -5,11 +5,11 @@
 
 @admin.register(StudentDetails)
 class StudentDetailsAdmin(admin.ModelAdmin):
-    list_display = ["user", "email", "first_name", "last_name", "matnum", "course"]
-    list_filter = ["course", "user__date_joined"]
-    search_fields = ["user__first_name", "user__last_name", "user__email", "matnum"]
-    fields = ["user", "email", "first_name", "last_name", "matnum", "course"]
-    readonly_fields = ["user", "email", "first_name", "last_name"]
+    list_display = ['user', 'email', 'first_name', 'last_name', 'matnum', 'course']
+    list_filter = ['course', 'user__date_joined']
+    search_fields = ['user__first_name', 'user__last_name', 'user__email', 'matnum']
+    fields = ['user', 'email', 'first_name', 'last_name', 'matnum', 'course']
+    readonly_fields = ['user', 'email', 'first_name', 'last_name']
 
     def first_name(self, obj):
         return obj.user.first_name
@@ -20,9 +20,9 @@ def last_name(self, obj):
     def email(self, obj):
         return '<a href="mailto:{email}">{email}</a>'.format(email=obj.user.email)
 
-    first_name.admin_order_field = "user__first_name"
-    last_name.admin_order_field = "user__last_name"
-    email.admin_order_field = "user__email"
+    first_name.admin_order_field = 'user__first_name'
+    last_name.admin_order_field = 'user__last_name'
+    email.admin_order_field = 'user__email'
     email.allow_tags = True
 
 

inloop/accounts/constance.py

@@ -6,28 +6,28 @@
 from inloop.common.validators import RegexSyntaxValidator
 
 config = OrderedDict()
-config["SIGNUP_ALLOWED"] = (False, mark_safe("Allow or disallow new users to sign up."))
-config["EMAIL_PATTERN"] = ("", mark_safe(
-    "A Python regular expression used to test email addresses during sign up. The "
-    "regex is compiled using <code>re.VERBOSE</code>, which means you can use "
-    "comments and whitespace (which will be ignored) to structure the regex."), "regex"
+config['SIGNUP_ALLOWED'] = (False, mark_safe('Allow or disallow new users to sign up.'))
+config['EMAIL_PATTERN'] = ('', mark_safe(
+    'A Python regular expression used to test email addresses during sign up. The '
+    'regex is compiled using <code>re.VERBOSE</code>, which means you can use '
+    'comments and whitespace (which will be ignored) to structure the regex.'), 'regex'
 )
-config["EMAIL_HELP_TEXT"] = ("", mark_safe(
-    "Form field help text with a human-friendly description of <code>EMAIL_PATTERN</code>."
+config['EMAIL_HELP_TEXT'] = ('', mark_safe(
+    'Form field help text with a human-friendly description of <code>EMAIL_PATTERN</code>.'
 ))
-config["EMAIL_ERROR_MESSAGE"] = ("", mark_safe(
+config['EMAIL_ERROR_MESSAGE'] = ('', mark_safe(
     "Form field error message in case <code>EMAIL_PATTERN</code> doesn't match."
 ))
 
 fieldsets = {
-    "Signup form settings": ["SIGNUP_ALLOWED", "EMAIL_PATTERN",
-                             "EMAIL_HELP_TEXT", "EMAIL_ERROR_MESSAGE"]
+    'Signup form settings': ['SIGNUP_ALLOWED', 'EMAIL_PATTERN',
+                             'EMAIL_HELP_TEXT', 'EMAIL_ERROR_MESSAGE']
 }
 
 fields = {
-    "regex": ["django.forms.CharField", {
-        "widget": "django.forms.Textarea",
-        "validators": [RegexSyntaxValidator(re.VERBOSE)],
-        "required": False
+    'regex': ['django.forms.CharField', {
+        'widget': 'django.forms.Textarea',
+        'validators': [RegexSyntaxValidator(re.VERBOSE)],
+        'required': False
     }],
 }

inloop/accounts/forms.py

@@ -37,25 +37,25 @@ def clean_email(self):
             # re.compile() succeeds. If it fails to compile now, there must be some
             # serious error which we can't fix here and it's better to crash.
             regex = re.compile(pattern, re.VERBOSE)
-            if not regex.search(self.cleaned_data["email"]):
+            if not regex.search(self.cleaned_data['email']):
                 raise ValidationError(markdown(config.EMAIL_ERROR_MESSAGE))
         return super().clean_email()
 
     def clean_username(self):
         """Ensure no duplicate user names exist, using case-insensitive comparison."""
-        username = self.cleaned_data.get("username")
+        username = self.cleaned_data.get('username')
         if User.objects.filter(username__iexact=username):
-            raise forms.ValidationError("A user with that username already exists.")
+            raise forms.ValidationError('A user with that username already exists.')
         return username
 
 
 class StudentDetailsForm(forms.ModelForm):
     class Meta:
         model = StudentDetails
-        fields = ["matnum", "course"]
+        fields = ['matnum', 'course']
 
 
 class UserChangeForm(forms.ModelForm):
     class Meta:
         model = User
-        fields = ["first_name", "last_name"]
+        fields = ['first_name', 'last_name']

inloop/accounts/models.py

@@ -9,16 +9,16 @@
 from django.utils.text import mark_safe
 
 INCOMPLETE_HINT = (
-    "Your user profile is incomplete. To ensure we can award bonus points to you, please "
-    "set your name and matriculation number on <a href=\"%s\">My Profile</a>."
+    'Your user profile is incomplete. To ensure we can award bonus points to you, please '
+    'set your name and matriculation number on <a href="%s">My Profile</a>.'
 )
 
 
-@receiver(user_logged_in, dispatch_uid="complete_profile_hint")
+@receiver(user_logged_in, dispatch_uid='complete_profile_hint')
 def complete_profile_hint(sender, user, request, **kwargs):
     """Show logged in users a hint if they do not have a complete profile."""
     if not user_profile_complete(user):
-        message = mark_safe(INCOMPLETE_HINT % reverse("accounts:profile"))
+        message = mark_safe(INCOMPLETE_HINT % reverse('accounts:profile'))
         # fail_silently needs to be set for unit tests using RequestFactory
         messages.warning(request, message, fail_silently=True)
 
@@ -41,20 +41,20 @@ def __str__(self):
 
 
 def default_course():
-    course, _ = Course.objects.get_or_create(name="Other")
+    course, _ = Course.objects.get_or_create(name='Other')
     return course.id
 
 
 class StudentDetails(models.Model):
     """Associate additional data to the user account."""
 
     class Meta:
-        verbose_name_plural = "Student details"
+        verbose_name_plural = 'Student details'
 
     user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
     matnum = models.CharField(
-        blank=True, verbose_name="Matriculation number", max_length=20, validators=[
-            RegexValidator(r'^[0-9]*$', "Please enter a numeric value or leave the field blank.")
+        blank=True, verbose_name='Matriculation number', max_length=20, validators=[
+            RegexValidator(r'^[0-9]*$', 'Please enter a numeric value or leave the field blank.')
         ]
     )
     course = models.ForeignKey(Course, default=default_course, on_delete=models.PROTECT)

inloop/accounts/urls.py

@@ -2,23 +2,23 @@
 
 from inloop.accounts import views
 
-app_name = "accounts"
+app_name = 'accounts'
 
 urlpatterns = [
-    url(r'^signup/$', views.signup, name="signup"),
-    url(r'^signup/closed/$', views.signup_closed, name="signup_closed"),
-    url(r'^signup/complete/$', views.signup_complete, name="signup_complete"),
-    url(r'^activate/complete/$', views.activation_complete, name="activation_complete"),
-    url(r'^activate/(?P<activation_key>[-:\w]+)/$', views.activate, name="activate"),
+    url(r'^signup/$', views.signup, name='signup'),
+    url(r'^signup/closed/$', views.signup_closed, name='signup_closed'),
+    url(r'^signup/complete/$', views.signup_complete, name='signup_complete'),
+    url(r'^activate/complete/$', views.activation_complete, name='activation_complete'),
+    url(r'^activate/(?P<activation_key>[-:\w]+)/$', views.activate, name='activate'),
 
-    url(r'^profile/$', views.profile, name="profile"),
-    url(r'^password/$', views.password_change, name="password_change"),
+    url(r'^profile/$', views.profile, name='profile'),
+    url(r'^password/$', views.password_change, name='password_change'),
 
-    url(r'^password_reset/$', views.password_reset, name="password_reset"),
-    url(r'^password_reset_done/', views.password_reset_done, name="password_reset_done"),
+    url(r'^password_reset/$', views.password_reset, name='password_reset'),
+    url(r'^password_reset_done/', views.password_reset_done, name='password_reset_done'),
     url(r'^password_reset_confirm/(?P<uidb64>[0-9A-Za-z_\-]+)/'
         r'(?P<token>[0-9A-Za-z]{1,13}-[0-9A-Za-z]{1,20})/$',
-        views.password_reset_confirm, name="password_reset_confirm"),
+        views.password_reset_confirm, name='password_reset_confirm'),
     url(r'^password_reset_confirm_done/$', views.password_reset_complete,
-        name="password_reset_complete"),
+        name='password_reset_complete'),
 ]

inloop/accounts/views.py

@@ -17,12 +17,12 @@
 
 
 class PasswordChangeView(DjangoPasswordChangeView):
-    success_url = reverse_lazy("accounts:profile")
-    template_name = "accounts/password_change_form.html"
+    success_url = reverse_lazy('accounts:profile')
+    template_name = 'accounts/password_change_form.html'
 
     def form_valid(self, form):
         response = super().form_valid(form)
-        messages.success(self.request, "Your password has been updated successfully.")
+        messages.success(self.request, 'Your password has been updated successfully.')
         return response
 
 
@@ -31,12 +31,12 @@ class ProfileView(LoginRequiredMixin, View):
     View and edit a User model and its related StudentDetails using one HTML form.
     """
 
-    template_name = "accounts/profile_form.html"
-    success_url = reverse_lazy("accounts:profile")
+    template_name = 'accounts/profile_form.html'
+    success_url = reverse_lazy('accounts:profile')
 
     def get(self, request):
         return TemplateResponse(request, self.template_name, context={
-            "forms": self.get_forms()
+            'forms': self.get_forms()
         })
 
     def post(self, request):
@@ -55,13 +55,13 @@ def get_forms(self, data=None):
 
     def forms_invalid(self, forms):
         return TemplateResponse(self.request, self.template_name, context={
-            "forms": forms
+            'forms': forms
         })
 
     def forms_valid(self, forms):
         for form in forms:
             form.save()
-        messages.success(self.request, "Your profile has been updated successfully.")
+        messages.success(self.request, 'Your profile has been updated successfully.')
         return HttpResponseRedirect(self.success_url)
 
 
@@ -70,45 +70,45 @@ def forms_valid(self, forms):
 
 
 class SignupView(HmacRegistrationView):
-    template_name = "accounts/signup_form.html"
+    template_name = 'accounts/signup_form.html'
     form_class = SignupForm
-    email_body_template = "accounts/activation_email.txt"
-    email_subject_template = "accounts/activation_email_subject.txt"
-    disallowed_url = reverse_lazy("accounts:signup_closed")
+    email_body_template = 'accounts/activation_email.txt'
+    email_subject_template = 'accounts/activation_email_subject.txt'
+    disallowed_url = reverse_lazy('accounts:signup_closed')
 
     def dispatch(self, request, *args, **kwargs):
         if request.user.is_authenticated:
-            return HttpResponseRedirect(reverse("home"))
+            return HttpResponseRedirect(reverse('home'))
         return super().dispatch(request, *args, **kwargs)
 
     def get_email_context(self, activation_key):
         context = super().get_email_context(activation_key)
-        context["request"] = self.request
+        context['request'] = self.request
         return context
 
     def get_success_url(self, user):
-        return reverse("accounts:signup_complete")
+        return reverse('accounts:signup_complete')
 
     def registration_allowed(self):
         return config.SIGNUP_ALLOWED
 
 
 class ActivationView(HmacActivationView):
-    template_name = "accounts/activation_failed.html"
+    template_name = 'accounts/activation_failed.html'
 
     def get_success_url(self, user):
-        return reverse("accounts:activation_complete")
+        return reverse('accounts:activation_complete')
 
 
 activate = ActivationView.as_view()
-activation_complete = TemplateView.as_view(template_name="accounts/activation_complete.html")
+activation_complete = TemplateView.as_view(template_name='accounts/activation_complete.html')
 signup = SignupView.as_view()
-signup_closed = TemplateView.as_view(template_name="accounts/signup_closed.html")
-signup_complete = TemplateView.as_view(template_name="accounts/signup_complete.html")
+signup_closed = TemplateView.as_view(template_name='accounts/signup_closed.html')
+signup_complete = TemplateView.as_view(template_name='accounts/signup_complete.html')
 
 password_reset = PasswordResetView.as_view(
-    success_url=reverse_lazy("accounts:password_reset_done"))
+    success_url=reverse_lazy('accounts:password_reset_done'))
 password_reset_done = PasswordResetDoneView.as_view()
 password_reset_confirm = PasswordResetConfirmView.as_view(
-    success_url=reverse_lazy("accounts:password_reset_complete"))
+    success_url=reverse_lazy('accounts:password_reset_complete'))
 password_reset_complete = PasswordResetCompleteView.as_view()

inloop/common/context_processors.py

@@ -4,5 +4,5 @@
 def current_site(request):
     """Context processor which populates the current site as ``site``."""
     return {
-        "site": get_current_site(request)
+        'site': get_current_site(request)
     }

inloop/common/middleware.py

@@ -16,13 +16,13 @@ def __init__(self, get_response):
 
     def __call__(self, request):
         try:
-            forwarded_for = request.META["HTTP_X_FORWARDED_FOR"]
+            forwarded_for = request.META['HTTP_X_FORWARDED_FOR']
         except KeyError:
             pass
         else:
             # HTTP_X_FORWARDED_FOR can be a comma-separated list of IPs.
             # The client's IP will be the first one.
-            forwarded_for = forwarded_for.split(",")[0].strip()
-            request.META["REMOTE_ADDR"] = forwarded_for
+            forwarded_for = forwarded_for.split(',')[0].strip()
+            request.META['REMOTE_ADDR'] = forwarded_for
 
         return self.get_response(request)