From 29bb735dc4748d4f03e30a4f8776d1063c688e80 Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Thu, 4 Feb 2021 00:25:00 +1100
Subject: [PATCH] Helper functions to automatically extract migration file info

---
 InvenTree/InvenTree/helpers.py       | 64 ++++++++++++++++++++++++++++
 InvenTree/company/test_migrations.py | 27 ++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/InvenTree/InvenTree/helpers.py b/InvenTree/InvenTree/helpers.py
index 99dc255dac..5cb6cc18dd 100644
--- a/InvenTree/InvenTree/helpers.py
+++ b/InvenTree/InvenTree/helpers.py
@@ -492,3 +492,67 @@ def addUserPermissions(user, permissions):
 
     for permission in permissions:
         addUserPermission(user, permission)
+
+
+def getMigrationFileNames(app):
+    """
+    Return a list of all migration filenames for provided app
+    """
+
+    local_dir = os.path.dirname(os.path.abspath(__file__))
+
+    migration_dir = os.path.join(local_dir, '..', app, 'migrations')
+
+    files = os.listdir(migration_dir)
+
+    # Regex pattern for migration files
+    pattern = r"^[\d]+_.*\.py$"
+
+    migration_files = []
+
+    for f in files:
+        if re.match(pattern, f):
+            migration_files.append(f)
+
+    return migration_files
+
+
+def getOldestMigrationFile(app, exclude_extension=True):
+    """
+    Return the filename associated with the oldest migration
+    """
+
+    oldest_num = -1
+    oldest_file = None
+
+    for f in getMigrationFileNames(app):
+        num = int(f.split('_')[0])
+        
+        if oldest_file is None or num < oldest_num:
+            oldest_num = num
+            oldest_file = f
+
+    if exclude_extension:
+        oldest_file = oldest_file.replace('.py', '')
+
+    return oldest_file
+
+def getNewestMigrationFile(app, exclude_extension=True):
+    """
+    Return the filename associated with the newest migration
+    """
+
+    newest_file = None
+    newest_num = -1
+
+    for f in getMigrationFileNames(app):
+        num = int(f.split('_')[0])
+
+        if newest_file is None or num > newest_num:
+            newest_num = num
+            newest_file = f
+
+    if exclude_extension:
+        newest_file = newest_file.replace('.py', '')
+
+    return newest_file
diff --git a/InvenTree/company/test_migrations.py b/InvenTree/company/test_migrations.py
index 16d9059f23..8ff2cc2a8b 100644
--- a/InvenTree/company/test_migrations.py
+++ b/InvenTree/company/test_migrations.py
@@ -4,6 +4,33 @@ Tests for the company model database migrations
 
 from django_test_migrations.contrib.unittest_case import MigratorTestCase
 
+from InvenTree import helpers
+
+
+class TestForwardMigrations(MigratorTestCase):
+
+    migrate_from = ('company', helpers.getOldestMigrationFile('company'))
+    migrate_to = ('company', helpers.getNewestMigrationFile('company'))
+
+    def prepare(self):
+        """
+        Create some simple Company data, and ensure that it migrates OK
+        """
+
+        Company = self.old_state.apps.get_model('company', 'company')
+
+        Company.objects.create(
+            name='MSPC',
+            description='Michael Scotts Paper Company',
+            is_supplier=True
+        )
+
+    def test_migrations(self):
+
+        Company = self.new_state.apps.get_model('company', 'company')
+
+        self.assertEqual(Company.objects.count(), 1)
+
 
 class TestManufacturerField(MigratorTestCase):
     """