Unit test intervention forms

* adds unit test for new/edit intervention forms
* improves code base for generating new identifiers

ema/models/ema.py

@@ -15,6 +15,7 @@ from django.urls import reverse
 
 from compensation.models import AbstractCompensation, PikMixin
 from ema.managers import EmaManager
+from ema.settings import EMA_IDENTIFIER_LENGTH, EMA_IDENTIFIER_TEMPLATE
 from ema.utils.quality import EmaQualityChecker
 from konova.models import AbstractDocument, generate_document_file_upload_path, RecordableObjectMixin, ShareableObjectMixin
 from konova.utils.message_templates import DATA_UNSHARED_EXPLANATION, DOCUMENT_REMOVED_TEMPLATE
@@ -38,6 +39,9 @@ class Ema(AbstractCompensation, ShareableObjectMixin, RecordableObjectMixin, Pik
     """
     objects = EmaManager()
 
+    identifier_length = EMA_IDENTIFIER_LENGTH
+    identifier_template = EMA_IDENTIFIER_TEMPLATE
+
     def __str__(self):
         return "{}".format(self.identifier)