From e417ff2b4dd06e2dc83384109d2a8612f221e168 Mon Sep 17 00:00:00 2001
From: Oliver Walters <oliver.henry.walters@gmail.com>
Date: Thu, 4 Feb 2021 00:44:37 +1100
Subject: [PATCH] Test migrations for build app

---
 InvenTree/InvenTree/helpers.py                |   6 +-
 .../build/migrations/0018_build_reference.py  |   2 +-
 InvenTree/build/test_migrations.py            | 118 ++++++++++++++++++
 3 files changed, 124 insertions(+), 2 deletions(-)
 create mode 100644 InvenTree/build/test_migrations.py

diff --git a/InvenTree/InvenTree/helpers.py b/InvenTree/InvenTree/helpers.py
index 5cb6cc18dd..33136d76ce 100644
--- a/InvenTree/InvenTree/helpers.py
+++ b/InvenTree/InvenTree/helpers.py
@@ -517,7 +517,7 @@ def getMigrationFileNames(app):
     return migration_files
 
 
-def getOldestMigrationFile(app, exclude_extension=True):
+def getOldestMigrationFile(app, exclude_extension=True, ignore_initial=True):
     """
     Return the filename associated with the oldest migration
     """
@@ -526,6 +526,10 @@ def getOldestMigrationFile(app, exclude_extension=True):
     oldest_file = None
 
     for f in getMigrationFileNames(app):
+
+        if ignore_initial and f.startswith('0001_initial'):
+            continue
+
         num = int(f.split('_')[0])
         
         if oldest_file is None or num < oldest_num:
diff --git a/InvenTree/build/migrations/0018_build_reference.py b/InvenTree/build/migrations/0018_build_reference.py
index bcf4f9b9d4..e8fd938b6a 100644
--- a/InvenTree/build/migrations/0018_build_reference.py
+++ b/InvenTree/build/migrations/0018_build_reference.py
@@ -9,7 +9,7 @@ def add_default_reference(apps, schema_editor):
     Best we can do is use the PK of the build order itself.
     """
 
-    Build = apps.get_model('build', 'Build')
+    Build = apps.get_model('build', 'build')
 
     count = 0
 
diff --git a/InvenTree/build/test_migrations.py b/InvenTree/build/test_migrations.py
new file mode 100644
index 0000000000..1e95cfb54e
--- /dev/null
+++ b/InvenTree/build/test_migrations.py
@@ -0,0 +1,118 @@
+"""
+Tests for the build model database migrations
+"""
+
+from django_test_migrations.contrib.unittest_case import MigratorTestCase
+
+from InvenTree import helpers
+
+
+class TestForwardMigrations(MigratorTestCase):
+    """
+    Test entire schema migration sequence for the build app
+    """
+
+    migrate_from = ('build', helpers.getOldestMigrationFile('build'))
+    migrate_to = ('build', helpers.getNewestMigrationFile('build'))
+
+    def prepare(self):
+        """
+        Create initial data!
+        """
+
+        Part = self.old_state.apps.get_model('part', 'part')
+
+        buildable_part = Part.objects.create(
+            name='Widget',
+            description='Buildable Part',
+            active=True,
+        )
+
+        with self.assertRaises(TypeError):
+            # Cannot set the 'assembly' field as it hasn't been added to the db schema
+            Part.objects.create(
+                name='Blorb',
+                description='ABCDE',
+                assembly=True
+            )
+
+        Build = self.old_state.apps.get_model('build', 'build')
+
+        Build.objects.create(
+            part=buildable_part,
+            title='A build of some stuff',
+            quantity=50
+        )
+
+    def test_items_exist(self):
+
+        Part = self.new_state.apps.get_model('part', 'part')
+
+        self.assertEqual(Part.objects.count(), 1)
+
+        Build = self.new_state.apps.get_model('build', 'build')
+
+        self.assertEqual(Build.objects.count(), 1)
+
+        # Check that the part object now has an assembly field
+        part = Part.objects.all().first()
+        part.assembly = True
+        part.save()
+        part.assembly = False
+        part.save()
+
+
+class TestReferenceMigration(MigratorTestCase):
+    """
+    Test custom migration which adds 'reference' field to Build model
+    """
+
+    migrate_from = ('build', helpers.getOldestMigrationFile('build'))
+    migrate_to = ('build', '0018_build_reference')
+
+    def prepare(self):
+        """
+        Create some builds
+        """
+
+        Part = self.old_state.apps.get_model('part', 'part')
+
+        part = Part.objects.create(
+            name='Part',
+            description='A test part'
+        )
+
+        Build = self.old_state.apps.get_model('build', 'build')
+
+        Build.objects.create(
+            part=part,
+            title='My very first build',
+            quantity=10
+        )
+
+        Build.objects.create(
+            part=part,
+            title='My very second build',
+            quantity=10
+        )
+
+        Build.objects.create(
+            part=part,
+            title='My very third build',
+            quantity=10
+        )
+
+        # Ensure that the builds *do not* have a 'reference' field
+        for build in Build.objects.all():
+            with self.assertRaises(AttributeError):
+                print(build.reference)
+
+    def test_build_reference(self):
+
+        Build = self.new_state.apps.get_model('build', 'build')
+
+        self.assertEqual(Build.objects.count(), 3)
+
+        # Check that the build reference is properly assigned
+        for build in Build.objects.all():
+            self.assertEqual(str(build.reference), str(build.pk))