Minor refactors:

- Renames s_assemble to s_brief
-  Link s_local to s_brief

apps/cic-ussd/tests/cic_ussd/db/migrations/test_migrations.py

@@ -0,0 +1,28 @@
+import pytest
+
+
+def test_single_head_revision(alembic_runner):
+    heads = alembic_runner.heads
+    head_count = len(heads)
+    assert head_count == 1
+
+
+def test_upgrade(alembic_runner):
+    try:
+        alembic_runner.migrate_up_to("head")
+    except RuntimeError:
+        pytest.fail('Failed to upgrade to the head revision.')
+
+
+def test_up_down_consistency(alembic_runner):
+    try:
+        for revision in alembic_runner.history.revisions:
+            alembic_runner.migrate_up_to(revision)
+    except RuntimeError:
+        pytest.fail('Failed to upgrade through each revision individually.')
+
+    try:
+        for revision in reversed(alembic_runner.history.revisions):
+            alembic_runner.migrate_down_to(revision)
+    except RuntimeError:
+        pytest.fail('Failed to downgrade through each revision individually.')