add new tests

Author: microslaw

pandas/tests/frame/methods/test_sample.py

@@ -134,6 +134,28 @@ def test_sample_inf_weights(self, obj):
         with pytest.raises(ValueError, match=msg):
             obj.sample(n=3, weights=weights_with_ninf)
 
+    def test_sample_unit_probabilities_raises(self, obj):
+        # GH#61516
+        high_variance_weights = [1] * 10
+        high_variance_weights[0] = 100
+        msg = (
+            "Invalid weights: If `replace`=False, "
+            "total unit probabilities have to be less than 1"
+        )
+        with pytest.raises(ValueError, match=msg):
+            obj.sample(n=2, weights=high_variance_weights, replace=False)
+
+        # edge case, n*max(weights)/sum(weights) == 1
+        edge_variance_weights = [1] * 10
+        edge_variance_weights[0] = 9
+        # should not raise
+        obj.sample(n=2, weights=edge_variance_weights, replace=False)
+
+        low_variance_weights = [1] * 10
+        low_variance_weights[0] = 8
+        # should not raise
+        obj.sample(n=2, weights=low_variance_weights, replace=False)
+
     def test_sample_zero_weights(self, obj):
         # All zeros raises errors