feat(validator): add 4 new validation functions

src/usepy/validator/__init__.py

@@ -1,4 +1,13 @@
 from .is_async_function import is_async_function
 from .is_url import is_url
+from .is_empty import is_empty
+from .validators import is_email, is_json, is_number
 
-__all__ = ["is_async_function", "is_url"]
+__all__ = [
+    "is_async_function",
+    "is_url",
+    "is_empty",
+    "is_email",
+    "is_json",
+    "is_number",
+]

src/usepy/validator/is_empty.py

@@ -0,0 +1,42 @@
+from typing import Any
+
+
+def is_empty(value: Any) -> bool:
+    """
+    Checks if a value is empty.
+
+    Empty values include: None, empty string, empty list, empty dict, empty set, 0, False.
+
+    Args:
+        value (Any): The value to check.
+
+    Returns:
+        bool: True if the value is considered empty, False otherwise.
+
+    Examples:
+        >>> is_empty(None)
+        True
+        >>> is_empty('')
+        True
+        >>> is_empty([])
+        True
+        >>> is_empty({})
+        True
+        >>> is_empty('hello')
+        False
+        >>> is_empty([1])
+        False
+    """
+    if value is None:
+        return True
+    if isinstance(value, (str, bytes, bytearray)):
+        # Strip whitespace before checking length
+        if isinstance(value, str):
+            value = value.strip()
+        return len(value) == 0
+    if isinstance(value, (list, tuple, set, dict)):
+        return len(value) == 0
+    # Check for numeric 0 and False
+    if value == 0 or value is False:
+        return True
+    return False

src/usepy/validator/validators.py

@@ -0,0 +1,83 @@
+import re
+from typing import Any
+
+
+def is_email(email: str) -> bool:
+    """
+    Checks if a string is a valid email address.
+
+    Args:
+        email (str): The email string to validate.
+
+    Returns:
+        bool: True if valid email format, False otherwise.
+
+    Examples:
+        >>> is_email('user@example.com')
+        True
+        >>> is_email('invalid.email')
+        False
+        >>> is_email('')
+        False
+    """
+    if not email:
+        return False
+    # Simple email regex for basic validation
+    pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
+    return bool(re.match(pattern, email))
+
+
+def is_json(json_string: str) -> bool:
+    """
+    Checks if a string is valid JSON.
+
+    Args:
+        json_string (str): The JSON string to validate.
+
+    Returns:
+        bool: True if valid JSON format, False otherwise.
+
+    Examples:
+        >>> is_json('{"key": "value"}')
+        True
+        >>> is_json('invalid json')
+        False
+    """
+    import json
+    try:
+        json.loads(json_string)
+        return True
+    except (json.JSONDecodeError, TypeError):
+        return False
+
+
+def is_number(value: Any) -> bool:
+    """
+    Checks if a value is a number (int, float, or numeric string).
+
+    Args:
+        value (Any): The value to check.
+
+    Returns:
+        bool: True if the value is a number, False otherwise.
+
+    Examples:
+        >>> is_number(123)
+        True
+        >>> is_number('123.45')
+        True
+        >>> is_number('not a number')
+        False
+        >>> is_number(None)
+        False
+    """
+    if isinstance(value, (int, float)):
+        return True
+    if isinstance(value, str) and value.strip():
+        # Check if string can be converted to float
+        try:
+            float(value)
+            return True
+        except ValueError:
+            return False
+    return False

tests/test_validator_new.py

@@ -0,0 +1,116 @@
+import pytest
+from usepy.validator import is_empty, is_email, is_json, is_number
+
+
+class TestIsEmpty:
+    """Tests for is_empty() function"""
+
+    def test_is_empty_none(self):
+        assert is_empty(None) is True
+
+    def test_is_empty_string(self):
+        assert is_empty('') is True
+        assert is_empty('   ') is True
+
+    def test_is_empty_list(self):
+        assert is_empty([]) is True
+
+    def test_is_empty_tuple(self):
+        assert is_empty(()) is True
+
+    def test_is_empty_dict(self):
+        assert is_empty({}) is True
+
+    def test_is_empty_set(self):
+        assert is_empty(set()) is True
+
+    def test_is_empty_zero(self):
+        assert is_empty(0) is True
+        assert is_empty(0.0) is True
+        assert is_empty(False) is True
+
+    def test_is_not_empty_string(self):
+        assert is_empty('hello') is False
+
+    def test_is_not_empty_list(self):
+        assert is_empty([1]) is False
+
+    def test_is_not_empty_dict(self):
+        assert is_empty({'a': 1}) is False
+
+
+class TestIsEmail:
+    """Tests for is_email() function"""
+
+    def test_valid_email(self):
+        assert is_email('user@example.com') is True
+        assert is_email('user.name@domain.co.uk') is True
+        assert is_email('test+tag@gmail.com') is True
+
+    def test_invalid_email(self):
+        assert is_email('invalid.email') is False
+        assert is_email('user@') is False
+        assert is_email('@example.com') is False
+        assert is_email('user@domain') is False
+
+    def test_empty_email(self):
+        assert is_email('') is False
+        assert is_email(None) is False
+
+
+class TestIsJson:
+    """Tests for is_json() function"""
+
+    def test_valid_json(self):
+        assert is_json('{"key": "value"}') is True
+        assert is_json('{"nested": {"key": [1, 2, 3]}}') is True
+        assert is_json('[1, 2, 3]') is True
+        assert is_json('null') is True
+        assert is_json('true') is True
+        assert is_json('"string"') is True
+        assert is_json('123') is True
+        assert is_json('null') is True
+
+    def test_invalid_json(self):
+        assert is_json('{"invalid": value}') is False
+        assert is_json('not json') is False
+        assert is_json('{') is False
+        assert is_json('') is False  # Empty string is NOT valid JSON
+
+    def test_none_is_json(self):
+        assert is_json(None) is False
+
+
+class TestIsNumber:
+    """Tests for is_number() function"""
+
+    def test_int_is_number(self):
+        assert is_number(123) is True
+        assert is_number(-456) is True
+
+    def test_float_is_number(self):
+        assert is_number(123.45) is True
+        assert is_number(-78.9) is True
+
+    def test_numeric_string_is_number(self):
+        assert is_number('123') is True
+        assert is_number('123.45') is True
+        assert is_number('-123') is True
+
+    def test_non_numeric_string_not_number(self):
+        assert is_number('abc') is False
+        assert is_number('12a34') is False
+        assert is_number('hello') is False
+
+    def test_zero_is_number(self):
+        assert is_number(0) is True
+        assert is_number(0.0) is True
+
+    def test_none_not_number(self):
+        assert is_number(None) is False
+
+    def test_empty_string_not_number(self):
+        assert is_number('') is False
+
+    def test_whitespace_not_number(self):
+        assert is_number('   ') is False