Do not require a captcha when using the API (#931)

* Do not require a captcha when using the API

This was trickier than expected, due to some side effects : when the
captcha is set to `True` via configuration, it doesn't change the
behavior directly of the ProjectForm class, but does so only when the
project form is used in the `web.py` module.

So, when just using the API (and not using the web.py module, for
instance during tests — manual or functional), no problem was shown,
and everything was working properly.

But at soon as somebody sees the "/" endpoint, the captcha was
required, by both the API and the `web.py` module.

This fixes it by adding a way to bypass the captcha with a new
`bypass_captcha` property on the form.

Prior to this commit, things were done by activating or deactivating a
"captcha" property on the class on-the-fly, which caused side-effects.

This is now using subclasses, which makes the code simpler to
understand, and less prone to side-effects.

Thanks @zorun for the idea.

ihatemoney/forms.py

@@ -228,13 +228,11 @@ class ProjectForm(EditProjectForm):
             )
             raise ValidationError(Markup(message))
 
-    @classmethod
+
-    def enable_captcha(cls):
+class ProjectFormWithCaptcha(ProjectForm):
-        captchaField = StringField(
+    captcha = StringField(
-            _("Which is a real currency: Euro or Petro dollar?"),
+        _("Which is a real currency: Euro or Petro dollar?"),
-            validators=[DataRequired()],
+    )
-        )
-        setattr(cls, "captcha", captchaField)
 
     def validate_captcha(form, field):
         if not field.data.lower() == _("euro"):

ihatemoney/tests/main_test.py

@@ -286,6 +286,7 @@ class CaptchaTestCase(IhatemoneyTestCase):
             assert len(models.Project.query.all()) == 1
 
     def test_api_project_creation_does_not_need_captcha(self):
+        self.client.get("/")
         resp = self.client.post(
             "/api/projects",
             data={

ihatemoney/web.py

@@ -47,6 +47,7 @@ from ihatemoney.forms import (
     MemberForm,
     PasswordReminder,
     ProjectForm,
+    ProjectFormWithCaptcha,
     ResetPasswordForm,
     UploadForm,
     get_billform_for,
@@ -264,8 +265,7 @@ def authenticate(project_id=None):
 
 def get_project_form():
     if current_app.config.get("ENABLE_CAPTCHA", False):
-        ProjectForm.enable_captcha()
+        return ProjectFormWithCaptcha()
-
     return ProjectForm()