test: add basic tests using hypothesis

It is segregated to its own file.

I am skipping the entire file using importorskip().

Mixing hypothesis tests with non-hypothesis tests is tricky.

Hypothesis uses decorators before test commands:

    @given(text())
    @settings(max_examples=_max_examples)

Pytest runs the decorators and the arguments as part of scanning the
file for tests. This means the decorator (given, settings ...) and the
strategies inside the decorators (e.g. text()) have to be defined
using a lambda or something. Only aborting at the top of the file
using importorskip prevents having to define all the symbols that
would be imported from hypothesis.

test/test_hypothesis.py

@@ -0,0 +1,96 @@
+import unittest
+
+import pytest
+
+pytest.importorskip("hypothesis")
+
+# ruff: noqa: E402
+from hypothesis import example, given, settings
+from hypothesis.strategies import binary, none, one_of, sampled_from, text
+
+from roundup.anypy.strings import b2s, s2b, s2u, u2s
+# ruff: noqa: I001  - yes I know I am using \ to continue the line...
+from roundup.password import PasswordValueError, encodePassword, \
+     h64decode, h64encode
+
+
+def Identity(x):
+    return x
+
+
+_max_examples = 1000
+
+
+class HypoTestStrings(unittest.TestCase):
+
+    @given(text())
+    @settings(max_examples=_max_examples)
+    def test_b2s(self, utf8_bytes):
+        self.assertEqual(b2s(utf8_bytes.encode("utf-8")), utf8_bytes)
+
+    @given(text())
+    @settings(max_examples=_max_examples)
+    def test_s2b(self, s):
+        self.assertTrue(isinstance(s2b(s), bytes))
+
+    @given(text())
+    @settings(max_examples=_max_examples)
+    @example("\U0001F600 hi there")  # smiley face emoji
+    def test_s2u_u2s_invertable(self, s):
+        self.assertEqual(u2s(s2u(s)), s)
+
+
+class HypoTestPassword(unittest.TestCase):
+
+    @given(binary())
+    @example(b"")
+    @settings(max_examples=_max_examples)
+    def test_h64encode_h64decode(self, s):
+
+        self.assertEqual(h64decode(h64encode(s)), s)
+
+    @given(one_of(none(), text()),
+           sampled_from(("PBKDF2S5", "PBKDF2", "SSHA",
+                         "SHA", "MD5", "crypt", "plaintext",
+                         "zot")))
+    @example("asd\x00df", "crypt")
+    @settings(max_examples=100 * _max_examples)
+    def test_encodePassword(self, password, scheme):
+
+        if	scheme == "crypt" and password and "\x00" in password:
+            with self.assertRaises(ValueError) as e:
+                encodePassword(password, scheme)
+            self.assertEqual(e.exception.args[0],
+                             "embedded null character")
+        elif scheme == "plaintext":
+            if password is not None:
+                self.assertEqual(encodePassword(password, scheme), password)
+            else:
+                self.assertEqual(encodePassword(password, scheme), "")
+        elif scheme == "zot":
+            with self.assertRaises(PasswordValueError) as e:
+                encodePassword(password, scheme)
+            self.assertEqual(e.exception.args[0],
+                             "Unknown encryption scheme 'zot'")
+        else:
+            # it shouldn't throw anything.
+            pw = encodePassword(password, scheme)
+
+            # verify format
+            if scheme in ["PBKDF2S5", "PBKDF2"]:
+                # 1000$XbSsijELEQbZZb1LlD7CFuotF/8$DdtssSlm.e
+                self.assertRegex(pw, r"^\d{4,8}\$.{27}\$.*")
+            elif scheme == "SSHA":
+                # vqDbjvs8rhrS1AJxHYEGGXQW3x7STAPgo7uCtnw4GYgU7FN5VYbZxccQYCC0eXOxSipLbtgBudH1vDRMNlG0uw==
+                self.assertRegex(pw, r"^[^=]*={0,3}$")
+            elif scheme == "SHA":
+                # da39a3ee5e6b4b0d3255bfef95601890afd80709'
+                self.assertRegex(pw, r"^[a-z0-9]{40}$")
+            elif scheme == "MD5":
+                # d41d8cd98f00b204e9800998ecf8427e'
+                self.assertRegex(pw, r"^[a-z0-9]{32}$")
+            elif scheme == "crypt":
+                # WqzFDzhi8MmoU
+                self.assertRegex(pw, r"^[A-z0-9./]{13}$")
+            else:
+                self.assertFalse("Unknown scheme: %s, val: %s" % (scheme, pw))