Add tests for MonteCarloConfig

qexpy/core/derived_value.py

@@ -100,6 +100,11 @@ def error_method(self, method: str):
             raise ValueError("The error method can only be 'derivative', 'monte-carlo', or 'auto'")
         self._error_method = method
 
+    @property
+    def mc(self):
+        """The MonteCarloConfig object for this value"""
+        return self._mc
+
 
 class MonteCarloConfig:
     """Stores all data and configurations of a Monte Carlo simulation."""
@@ -136,6 +141,6 @@ def sample_size(self, size: int):
     @property
     def samples(self):
         """The array of simulated samples"""
-        if self._samples is None:
+        if self._samples is None or len(self._samples) != self.sample_size:
             self._samples = q.core.monte_carlo(self._formula, self.sample_size)
         return self._samples

tests/core/test_monte_carlo.py

@@ -0,0 +1,43 @@
+"""Tests for more fine-grained control of the Monte Carlo error method"""
+
+import pytest
+
+import qexpy as q
+
+
+class TestMonteCarloConfig:
+    """Tests the MonteCarloConfig class"""
+
+    @pytest.fixture(autouse=True)
+    def cleanup(self):
+        """Cleans up global configurations"""
+        yield
+        q.reset_option()
+
+    def test_sample_size(self):
+        """Tests the Monte Carlo sample size"""
+
+        m1 = q.Measurement(1.23, 0.02)
+        m2 = q.Measurement(4.56, 0.03)
+        res = m1 + m2
+        res.error_method = "monte-carlo"
+        assert res.mc.sample_size == 100000
+        assert len(res.mc.samples) == 100000
+
+        q.options.error.mc.sample_size = 1000
+        assert res.mc.sample_size == 1000
+        assert len(res.mc.samples) == 1000
+
+        res.mc.sample_size = 200
+        assert res.mc.sample_size == 200
+        assert len(res.mc.samples) == 200
+
+    def test_invalid_sample_size(self):
+        """Tests that error is raised for invalid sample sizes"""
+
+        m1 = q.Measurement(1.23, 0.02)
+        m2 = q.Measurement(4.56, 0.03)
+        res = m1 + m2
+        res.error_method = "monte-carlo"
+        with pytest.raises(ValueError, match="The sample size must be a positive integer!"):
+            res.mc.sample_size = -100