diff --git a/src/color_converter.py b/src/color_converter.py
new file mode 100644
index 00000000..fab48043
--- /dev/null
+++ b/src/color_converter.py
@@ -0,0 +1,36 @@
+def rgb_to_hex(*args):
+    """
+    Convert RGB color values to a hexadecimal color code.
+    
+    Args:
+        *args: Either 3 individual integer values (r, g, b) 
+               or a single tuple/list of 3 RGB values
+    
+    Returns:
+        str: Hexadecimal color code (e.g., '#FF0000' for bright red)
+    
+    Raises:
+        ValueError: If RGB values are not in the range 0-255 
+                    or incorrect number of arguments is provided
+    """
+    # Handle different input formats
+    if len(args) == 1 and isinstance(args[0], (tuple, list)):
+        rgb = args[0]
+    elif len(args) == 3:
+        rgb = args
+    else:
+        raise ValueError("Input must be either 3 separate values or a single tuple/list of 3 values")
+    
+    # Validate input
+    if len(rgb) != 3:
+        raise ValueError("Exactly 3 color values (R, G, B) are required")
+    
+    # Check each value is in valid range
+    for color in rgb:
+        if not isinstance(color, int):
+            raise ValueError("RGB values must be integers")
+        if color < 0 or color > 255:
+            raise ValueError("RGB values must be between 0 and 255")
+    
+    # Convert to hexadecimal
+    return '#{:02X}{:02X}{:02X}'.format(rgb[0], rgb[1], rgb[2])
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diff --git a/tests/test_color_converter.py b/tests/test_color_converter.py
new file mode 100644
index 00000000..91ea45cc
--- /dev/null
+++ b/tests/test_color_converter.py
@@ -0,0 +1,54 @@
+import pytest
+from src.color_converter import rgb_to_hex
+
+def test_rgb_to_hex_individual_values():
+    """Test conversion with individual RGB values"""
+    assert rgb_to_hex(255, 0, 0) == '#FF0000'
+    assert rgb_to_hex(0, 255, 0) == '#00FF00'
+    assert rgb_to_hex(0, 0, 255) == '#0000FF'
+
+def test_rgb_to_hex_tuple():
+    """Test conversion with RGB tuple"""
+    assert rgb_to_hex((255, 0, 0)) == '#FF0000'
+    assert rgb_to_hex((0, 255, 0)) == '#00FF00'
+    assert rgb_to_hex((0, 0, 255)) == '#0000FF'
+
+def test_rgb_to_hex_mixed_colors():
+    """Test conversion with mixed RGB values"""
+    assert rgb_to_hex(128, 128, 128) == '#808080'
+    assert rgb_to_hex(255, 165, 0) == '#FFA500'
+
+def test_rgb_to_hex_edge_cases():
+    """Test edge case values"""
+    assert rgb_to_hex(0, 0, 0) == '#000000'
+    assert rgb_to_hex(255, 255, 255) == '#FFFFFF'
+
+def test_rgb_to_hex_invalid_input():
+    """Test error handling for invalid inputs"""
+    # Too few arguments
+    with pytest.raises(ValueError):
+        rgb_to_hex(255, 0)
+    
+    # Too many arguments
+    with pytest.raises(ValueError):
+        rgb_to_hex(255, 0, 0, 0)
+    
+    # Non-integer values
+    with pytest.raises(ValueError):
+        rgb_to_hex(255.5, 0, 0)
+    
+    # Out of range values
+    with pytest.raises(ValueError):
+        rgb_to_hex(256, 0, 0)
+    
+    # Negative values
+    with pytest.raises(ValueError):
+        rgb_to_hex(-1, 0, 0)
+    
+    # Invalid input type
+    with pytest.raises(ValueError):
+        rgb_to_hex("255", "0", "0")
+    
+    # Invalid tuple/list
+    with pytest.raises(ValueError):
+        rgb_to_hex([255, 0])
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