Add small unit tests for `pyfastani.Sketch` behaviours without data dependency

pyfastani/tests/test_sketch.py

+import os
+import sys
+import unittest
+import warnings
+
+import pyfastani
+
+
+class TestSketch(unittest.TestCase):
+
+    def test_init_errors(self):
+        """Check that constructor parameters are properly validated.
+        """
+        self.assertRaises(TypeError, pyfastani.Sketch, k="1")
+        self.assertRaises(TypeError, pyfastani.Sketch, fragment_length="1")
+        self.assertRaises(TypeError, pyfastani.Sketch, minimum_fraction="0.5")
+
+        self.assertRaises(OverflowError, pyfastani.Sketch, k=2**32)
+        self.assertRaises(ValueError, pyfastani.Sketch, k=0)
+        self.assertRaises(ValueError, pyfastani.Sketch, p_value=-1.0)
+        self.assertRaises(ValueError, pyfastani.Sketch, percentage_identity=-1.0)
+        self.assertRaises(ValueError, pyfastani.Sketch, percentage_identity=200.0)
+
+    def test_reinit(self):
+        """Check that calling `__init__` more than once does not crash.
+        """
+        sketch = pyfastani.Sketch()
+        sketch.add_genome("test", "ATGC"*1000)
+        self.assertEqual(sketch.names, ["test"])
+
+        sketch.__init__()
+        self.assertEqual(sketch.names, [])
+
+    def test_add_draft_warnings(self):
+        """Check that `Sketch.add_draft` raises warnings as expected.
+        """
+        sketch = pyfastani.Sketch()
+        with warnings.catch_warnings(record=True) as catch:
+            sketch.add_draft("short_seq", ["ATGC"*1000, "ATGC"])
+            self.assertEqual(len(catch), 1)  # second sequence is too short
+
+    def test_add_sequence_short(self):
+        """Check that a sequence too short to be hashed is still recorded.
+        """
+        sketch = pyfastani.Sketch()
+        with warnings.catch_warnings(record=True) as catch:
+            warnings.simplefilter("ignore")
+            sketch.add_draft("short_seq", ["ATGC"*1000, "ATGC"])
+            self.assertEqual(sketch.names, ["short_seq"])