Add tests for SQS structures

tests/test_sqs.py

@@ -0,0 +1,63 @@
+import unittest
+from ase.build import bulk
+import structuretoolkit as stk
+
+
+class SQSTestCase(unittest.TestCase):
+    def test_sqs_structures_no_stats(self):
+        structures_lst = stk.build.sqs_structures(
+            structure=bulk("Au", cubic=True).repeat([2, 2, 2]),
+            mole_fractions={"Cu": 0.5, "Au": 0.5},
+            weights=None,
+            objective=0.0,
+            iterations=1e6,
+            output_structures=10,
+            mode="random",
+            num_threads=None,
+            prefactors=None,
+            pair_weights=None,
+            rtol=None,
+            atol=None,
+            which=None,
+            shell_distances=None,
+            minimal=True,
+            similar=True,
+            return_statistics=False,
+        )
+        self.assertEqual(len(structures_lst), 10)
+        symbols_lst = [s.get_chemical_symbols() for s in structures_lst]
+        for s in symbols_lst:
+            self.assertEqual(len(s), 32)
+            for el in ["Au", "Cu"]:
+                self.assertAlmostEqual(s.count(el)/len(s), 0.5)
+
+    def test_sqs_structures_with_stats(self):
+        structures_lst, sro_breakdown, num_iterations, cycle_time = stk.build.sqs_structures(
+            structure=bulk("Au", cubic=True).repeat([2, 2, 2]),
+            mole_fractions={"Cu": 0.5, "Au": 0.5},
+            weights=None,
+            objective=0.0,
+            iterations=1e6,
+            output_structures=10,
+            mode="random",
+            num_threads=None,
+            prefactors=None,
+            pair_weights=None,
+            rtol=None,
+            atol=None,
+            which=None,
+            shell_distances=None,
+            minimal=True,
+            similar=True,
+            return_statistics=True,
+        )
+        self.assertEqual(len(structures_lst), 10)
+        symbols_lst = [s.get_chemical_symbols() for s in structures_lst]
+        for s in symbols_lst:
+            self.assertEqual(len(s), 32)
+            for el in ["Au", "Cu"]:
+                self.assertAlmostEqual(s.count(el)/len(s), 0.5)
+        for sro in sro_breakdown:
+            self.assertEqual(list(sro.keys()), ['Cu-Cu', 'Cu-Au', 'Au-Au'])
+        self.assertEqual(num_iterations, 1000000.0)
+        self.assertTrue(cycle_time < 10)