test: unit, integration and e2e tests

Task: MIL-002#6

tests/unit/domain/test_password_generator.py

@@ -0,0 +1,35 @@
+import random
+
+from password_manager import constants
+from password_manager.domain.password_generator import generate_password
+
+
+def _count(password: str, alphabet: str) -> int:
+    return sum(1 for char in password if char in alphabet)
+
+
+def test_generate_password_length_within_bounds() -> None:
+    low = constants.MIN_LETTERS + constants.MIN_SYMBOLS + constants.MIN_DIGITS
+    high = constants.MAX_LETTERS + constants.MAX_SYMBOLS + constants.MAX_DIGITS
+    for seed in range(50):
+        assert low <= len(generate_password(random.Random(seed))) <= high
+
+
+def test_generate_password_uses_all_three_classes_within_bounds() -> None:
+    for seed in range(50):
+        password = generate_password(random.Random(seed))
+        letters = _count(password, constants.LETTERS)
+        symbols = _count(password, constants.SYMBOLS)
+        digits = _count(password, constants.DIGITS)
+        assert constants.MIN_LETTERS <= letters <= constants.MAX_LETTERS
+        assert constants.MIN_SYMBOLS <= symbols <= constants.MAX_SYMBOLS
+        assert constants.MIN_DIGITS <= digits <= constants.MAX_DIGITS
+        assert letters + symbols + digits == len(password)
+
+
+def test_generate_password_is_reproducible_with_same_seed() -> None:
+    assert generate_password(random.Random(7)) == generate_password(random.Random(7))
+
+
+def test_generate_password_default_source_works() -> None:
+    assert generate_password()