add PrefixIdentifier() and some tests

tests/test_strtools.py

@@ -0,0 +1,38 @@
+
+
+
+import unittest
+
+from suou.strtools import PrefixIdentifier
+
+class TestStrtools(unittest.TestCase):
+    def setUp(self) -> None:
+        ...
+
+    def tearDown(self) -> None:
+        ...
+
+    def test_PrefixIdentifier_empty(self):
+        pi = PrefixIdentifier(None)
+        self.assertEqual(pi.hello, 'hello')
+        self.assertEqual(pi['with spaces'], 'with spaces')
+        self.assertEqual(pi['\x1b\x00'], '\x1b\0')
+        self.assertEqual(pi.same_thing, pi['same_thing'])
+
+        with self.assertRaises(TypeError):
+            pi[0]
+
+        self.assertEqual(PrefixIdentifier(None), PrefixIdentifier(''))
+
+    def test_PrefixIdentifier_invalid(self):
+        with self.assertRaises(TypeError):
+            pi = PrefixIdentifier(1)
+            pi.hello
+
+        with self.assertRaises(TypeError):
+            PrefixIdentifier([99182])
+        
+        with self.assertRaises(TypeError):
+            PrefixIdentifier(b'alpha_')
+    
+