fix: error in updating LMS Batch membership

The validation was always failing when trying to updating an LMS Batch
Membership document. This was due to a bug in the validation logic that
was considering itself as a duplicate record. This has been fixed.

Also added tests to verify that.

community/lms/doctype/lms_batch_membership/lms_batch_membership.py

@@ -17,7 +17,8 @@ class LMSBatchMembership(Document):
         previous_membership = frappe.db.get_value("LMS Batch Membership",
             filters={
                 "member": self.member,
-                "batch": self.batch, "name": ["!=", self.name]
+                "batch": self.batch,
+                "name": ["!=", self.name]
             },
             fieldname=["member_type","member"],
             as_dict=1)
@@ -30,7 +31,8 @@ class LMSBatchMembership(Document):
         course = frappe.db.get_value("LMS Batch", self.batch, "course")
         previous_membership = frappe.get_all("LMS Batch Membership",
                                     filters={
-                                        "member": self.member
+                                        "member": self.member,
+                                        "name": ["!=", self.name]
                                     },
                                     fields=["batch", "member_type"]
                                 )

community/lms/doctype/lms_batch_membership/test_lms_batch_membership.py

@@ -3,8 +3,77 @@
 # See license.txt
 from __future__ import unicode_literals
 
-# import frappe
+import frappe
 import unittest
 
 class TestLMSBatchMembership(unittest.TestCase):
-	pass
+    def setUp(self):
+        frappe.db.sql("DELETE FROM `tabLMS Batch Membership`")
+        frappe.db.sql("DELETE FROM `tabLMS Batch`")
+        frappe.db.sql('delete from `tabLMS Course Mentor Mapping`')
+        frappe.db.sql("DELETE FROM `tabLMS Course`")
+        frappe.db.sql("DELETE FROM `tabCommunity Member` where email like '%@test.com'")
+        frappe.db.sql("DELETE FROM `tabUser` where email like '%@test.com'")
+
+    def new_course_batch(self):
+        course = frappe.get_doc({
+            "doctype": "LMS Course",
+            "name": "test-course",
+            "title": "Test Course",
+            "short_code": "XX"
+        })
+        course.insert()
+
+        self.new_user("mentor@test.com", "Test Mentor")
+        # without this, the creating batch will fail
+        course.add_mentor("mentor@test.com")
+
+        frappe.session.user = "mentor@test.com"
+
+        batch = frappe.get_doc({
+            "doctype": "LMS Batch",
+            "name": "test-batch",
+            "title": "Test Batch",
+            "course": course.name
+        })
+        batch.insert(ignore_permissions=True)
+
+        frappe.session.user = "Administrator"
+        return course, batch
+
+    def new_user(self, email="test@test.com", full_name="Test User"):
+        user = frappe.get_doc({
+            "doctype": "User",
+            "name": email,
+            "email": email,
+            "first_name": full_name,
+        })
+        user.insert()
+        return user
+
+    def add_membership(self, batch_name, member_name, member_type="Student"):
+        doc = frappe.get_doc({
+            "doctype": "LMS Batch Membership",
+            "batch": batch_name,
+            "member": member_name,
+            "member_type": member_type
+        })
+        doc.insert()
+        return doc
+
+    def test_membership(self):
+        course, batch = self.new_course_batch()
+        member = self.new_user("test01@test.com")
+        membership = self.add_membership(batch.name, member.name)
+
+        assert membership.course == course.name
+        assert membership.member_name == member.full_name
+
+    def test_membership_change_role(self):
+        course, batch = self.new_course_batch()
+        member = self.new_user("test01@test.com")
+        membership = self.add_membership(batch.name, member.name)
+
+        # it should be possible to change role
+        membership.role = "Admin"
+        membership.save()