feat: Add fraction simplification dataset to arithmetic module

tests/test_fraction_simplification.py

@@ -0,0 +1,123 @@
+import pytest
+from math import gcd
+from reasoning_gym.arithmetic import FractionSimplificationDataset, FractionSimplificationConfig
+
+
+def test_fraction_config_validation():
+    """Test that invalid configs raise appropriate errors"""
+    with pytest.raises(AssertionError):
+        config = FractionSimplificationConfig(min_value=0)  # Should be positive
+        config.validate()
+    
+    with pytest.raises(AssertionError):
+        config = FractionSimplificationConfig(min_value=100, max_value=50)  # max should be > min
+        config.validate()
+    
+    with pytest.raises(AssertionError):
+        config = FractionSimplificationConfig(min_factor=1)  # Should be >= 2
+        config.validate()
+    
+    with pytest.raises(AssertionError):
+        config = FractionSimplificationConfig(min_factor=5, max_factor=3)  # max should be >= min
+        config.validate()
+
+
+def test_fraction_deterministic():
+    """Test that dataset generates same items with same seed"""
+    config = FractionSimplificationConfig(seed=42, size=10)
+    dataset1 = FractionSimplificationDataset(config)
+    dataset2 = FractionSimplificationDataset(config)
+    
+    for i in range(len(dataset1)):
+        assert dataset1[i] == dataset2[i]
+
+
+def test_fraction_items():
+    """Test basic properties of generated items"""
+    config = FractionSimplificationConfig(
+        min_value=1,
+        max_value=20,
+        min_factor=2,
+        max_factor=5,
+        size=50,
+        seed=42
+    )
+    dataset = FractionSimplificationDataset(config)
+    
+    for i in range(len(dataset)):
+        item = dataset[i]
+        assert isinstance(item, dict)
+        assert "question" in item
+        assert "answer" in item
+        assert "metadata" in item
+        
+        # Verify the metadata contains all expected fields
+        metadata = item["metadata"]
+        assert "numerator" in metadata
+        assert "denominator" in metadata
+        assert "simplified_numerator" in metadata
+        assert "simplified_denominator" in metadata
+        assert "reduction_factor" in metadata
+        
+        # Verify the numbers are within configured range
+        assert config.min_value <= metadata["simplified_numerator"] <= config.max_value
+        assert config.min_value <= metadata["simplified_denominator"] <= config.max_value
+        
+        # Verify the reduction is correct
+        num = metadata["numerator"]
+        den = metadata["denominator"]
+        simple_num = metadata["simplified_numerator"]
+        simple_den = metadata["simplified_denominator"]
+        factor = metadata["reduction_factor"]
+        
+        assert num == simple_num * factor
+        assert den == simple_den * factor
+        
+        # Verify the simplified fraction is actually in lowest terms
+        assert gcd(simple_num, simple_den) == 1
+
+
+def test_fraction_ranges():
+    """Test that generated numbers respect value constraints"""
+    config = FractionSimplificationConfig(
+        min_value=5,
+        max_value=15,
+        min_factor=3,
+        max_factor=4,
+        size=20,
+        seed=42
+    )
+    dataset = FractionSimplificationDataset(config)
+    
+    for i in range(len(dataset)):
+        item = dataset[i]
+        metadata = item["metadata"]
+        factor = metadata["reduction_factor"]
+        
+        # Check factor is within bounds
+        assert 3 <= factor <= 4
+        
+        # Check simplified values are within bounds
+        assert 5 <= metadata["simplified_numerator"] <= 15
+        assert 5 <= metadata["simplified_denominator"] <= 15
+
+
+def test_fraction_iteration():
+    """Test that iteration works correctly"""
+    config = FractionSimplificationConfig(size=5, seed=42)
+    dataset = FractionSimplificationDataset(config)
+    
+    # Test manual iteration
+    items = []
+    for item in dataset:
+        items.append(item)
+    assert len(items) == config.size
+    
+    # Test list conversion
+    items = list(dataset)
+    assert len(items) == config.size
+    
+    # Test multiple iterations yield same results
+    first_items = list(dataset)
+    second_items = list(dataset)
+    assert first_items == second_items