Add test for sequences.

tests/integration/test_project_references_sequences.py

@@ -0,0 +1,34 @@
+import pytest
+
+@pytest.fixture
+def seq():
+    from taiga.projects.references import sequences as seq
+    return seq
+
+@pytest.mark.django_db
+def test_sequences(seq):
+    seqname = "foo"
+    assert not seq.exists(seqname)
+
+    # Create and check values
+    seq.create(seqname)
+    assert seq.exists(seqname)
+    assert seq.next_value(seqname) == 1
+    assert seq.next_value(seqname) == 2
+
+    # Delete sequence
+    seq.delete(seqname)
+    assert not seq.exists(seqname)
+
+    # Create new seq with same name
+    # after previously deleted it
+    seq.create(seqname)
+    assert seq.next_value(seqname) == 1
+
+    # Alter sequence
+    seq.alter(seqname, 4)
+    assert seq.next_value(seqname) == 5
+
+    # Delete after alter
+    seq.delete(seqname)
+    assert not seq.exists(seqname)