Add 116 unit tests for core utility modules (#4269)

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Shuchang Zheng <wintonzheng0325@gmail.com>

tests/unit_tests/test_strings.py

@@ -0,0 +1,91 @@
+"""Tests for string utility functions."""
+
+import string
+
+from skyvern.utils.strings import RANDOM_STRING_POOL, generate_random_string
+
+
+class TestRandomStringPool:
+    """Tests for RANDOM_STRING_POOL constant."""
+
+    def test_pool_contains_letters(self):
+        """Pool should contain all ASCII letters."""
+        for char in string.ascii_letters:
+            assert char in RANDOM_STRING_POOL
+
+    def test_pool_contains_digits(self):
+        """Pool should contain all digits."""
+        for char in string.digits:
+            assert char in RANDOM_STRING_POOL
+
+    def test_pool_size(self):
+        """Pool should have expected size (26*2 + 10 = 62)."""
+        assert len(RANDOM_STRING_POOL) == 62
+
+
+class TestGenerateRandomString:
+    """Tests for generate_random_string function."""
+
+    def test_default_length(self):
+        """Default length should be 5."""
+        result = generate_random_string()
+        assert len(result) == 5
+
+    def test_custom_length(self):
+        """Custom length should be respected."""
+        for length in [1, 10, 50, 100]:
+            result = generate_random_string(length)
+            assert len(result) == length
+
+    def test_zero_length(self):
+        """Zero length should return empty string."""
+        result = generate_random_string(0)
+        assert result == ""
+
+    def test_returns_string(self):
+        """Should return a string type."""
+        result = generate_random_string()
+        assert isinstance(result, str)
+
+    def test_only_alphanumeric(self):
+        """Result should only contain alphanumeric characters."""
+        result = generate_random_string(100)
+        for char in result:
+            assert char in RANDOM_STRING_POOL
+
+    def test_randomness(self):
+        """Multiple calls should produce different results (with high probability)."""
+        results = [generate_random_string(20) for _ in range(10)]
+        # All results should be unique (statistically extremely likely with length 20)
+        assert len(set(results)) == 10
+
+    def test_distribution(self):
+        """Characters should be reasonably distributed."""
+        # Generate a long string and check distribution
+        result = generate_random_string(10000)
+        char_counts = {}
+        for char in result:
+            char_counts[char] = char_counts.get(char, 0) + 1
+
+        # Each character should appear at least once in 10000 characters
+        # (statistically extremely likely)
+        assert len(char_counts) > 50  # Most of the 62 chars should appear
+
+    def test_contains_letters(self):
+        """Generated strings should typically contain letters."""
+        # With 62 possible chars and length 100, very likely to have letters
+        result = generate_random_string(100)
+        has_letter = any(c in string.ascii_letters for c in result)
+        assert has_letter
+
+    def test_contains_digits(self):
+        """Generated strings should typically contain digits."""
+        # With 62 possible chars and length 100, very likely to have digits
+        result = generate_random_string(100)
+        has_digit = any(c in string.digits for c in result)
+        assert has_digit
+
+    def test_large_length(self):
+        """Should handle large lengths."""
+        result = generate_random_string(10000)
+        assert len(result) == 10000