diff --git a/src/prime_checker.py b/src/prime_checker.py
new file mode 100644
index 0000000..05a7491
--- /dev/null
+++ b/src/prime_checker.py
@@ -0,0 +1,35 @@
+def is_prime(number: int) -> bool:
+    """
+    Check if a given number is prime.
+    
+    Args:
+        number (int): The number to check for primality.
+    
+    Returns:
+        bool: True if the number is prime, False otherwise.
+    
+    Raises:
+        ValueError: If the input is not an integer.
+    """
+    # Check for invalid input
+    if not isinstance(number, int):
+        raise ValueError("Input must be an integer")
+    
+    # Handle edge cases
+    if number < 2:
+        return False
+    
+    # Optimization for small numbers
+    if number == 2:
+        return True
+    
+    # Even numbers greater than 2 are not prime
+    if number % 2 == 0:
+        return False
+    
+    # Check odd divisors up to the square root of the number
+    for divisor in range(3, int(number**0.5) + 1, 2):
+        if number % divisor == 0:
+            return False
+    
+    return True
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diff --git a/tests/test_prime_checker.py b/tests/test_prime_checker.py
new file mode 100644
index 0000000..ab90258
--- /dev/null
+++ b/tests/test_prime_checker.py
@@ -0,0 +1,50 @@
+import pytest
+from src.prime_checker import is_prime
+
+def test_is_prime_small_primes():
+    """Test small known prime numbers."""
+    assert is_prime(2) == True
+    assert is_prime(3) == True
+    assert is_prime(5) == True
+    assert is_prime(7) == True
+    assert is_prime(11) == True
+    assert is_prime(13) == True
+
+def test_is_prime_small_composites():
+    """Test small known composite numbers."""
+    assert is_prime(1) == False
+    assert is_prime(4) == False
+    assert is_prime(6) == False
+    assert is_prime(8) == False
+    assert is_prime(9) == False
+    assert is_prime(10) == False
+    assert is_prime(12) == False
+
+def test_is_prime_larger_numbers():
+    """Test larger prime and composite numbers."""
+    assert is_prime(17) == True
+    assert is_prime(19) == True
+    assert is_prime(23) == True
+    assert is_prime(29) == True
+    
+    assert is_prime(15) == False
+    assert is_prime(21) == False
+    assert is_prime(25) == False
+    assert is_prime(27) == False
+
+def test_is_prime_edge_cases():
+    """Test edge cases."""
+    assert is_prime(0) == False
+    assert is_prime(1) == False
+    assert is_prime(-1) == False
+    assert is_prime(-2) == False
+    assert is_prime(-17) == False
+
+def test_is_prime_invalid_input():
+    """Test handling of invalid input types."""
+    with pytest.raises(ValueError):
+        is_prime(3.14)
+    with pytest.raises(ValueError):
+        is_prime("17")
+    with pytest.raises(ValueError):
+        is_prime(None)
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