test: add is_sorted to tests

tests/test_is_sortable.py

@@ -0,0 +1,27 @@
+import eblob_kit
+
+from collections import namedtuple
+
+
+DummyRecord = namedtuple('DummyRecord', 'a b')
+
+
+def test_sequence_is_sorted_default_key():
+    sorted_sequence = [-1, 1, 2, 3, 4, 5, 10, 100, 1000]
+    assert eblob_kit.is_sorted(sorted_sequence)
+
+
+def test_sequence_not_sorted_default_key():
+    non_sorted_sequence = [-1, 1, 2, 3, 4, 5, 10, 100, 99, 1000]
+    assert not eblob_kit.is_sorted(non_sorted_sequence)
+
+
+def test_sequence_is_sorted_custom_key():
+    sequence_length = 10
+    sequence = [
+        DummyRecord(i, sequence_length - i) for i in xrange(sequence_length)
+    ]
+
+    assert eblob_kit.is_sorted(sequence)
+    assert eblob_kit.is_sorted(sequence, lambda x: x.a)
+    assert not eblob_kit.is_sorted(sequence, lambda x: x.b)