[commons-statistics] 27/35: Increase AbstractDiscreteDistribution test coverage.

[ah...@apache.org]

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aherbert pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-statistics.git

commit c170b7ac4f52d2a647154ae6a4162a70d198e7f5
Author: aherbert <ah...@apache.org>
AuthorDate: Tue Jun 23 16:59:38 2020 +0100

    Increase AbstractDiscreteDistribution test coverage.
---
 .../AbstractDiscreteDistributionTest.java          | 74 ++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/AbstractDiscreteDistributionTest.java b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/AbstractDiscreteDistributionTest.java
index cbb42ab..3166dac 100644
--- a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/AbstractDiscreteDistributionTest.java
+++ b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/AbstractDiscreteDistributionTest.java
@@ -73,6 +73,80 @@ public class AbstractDiscreteDistributionTest {
         }
     }
 
+    @Test
+    public void testInverseCumulativeProbabilityExtremes() {
+        // Require a lower bound of MIN_VALUE and the cumulative probability
+        // at that bound to be lower/higher than the argument cumulative probability.
+        final DiscreteDistribution dist = new AbstractDiscreteDistribution() {
+            @Override
+            public double probability(int x) {
+                return 0;
+            }
+            @Override
+            public double cumulativeProbability(int x) {
+                return x == Integer.MIN_VALUE ? 0.1 : 1.0;
+            }
+            @Override
+            public double getMean() {
+                return 0;
+            }
+            @Override
+            public double getVariance() {
+                return 0;
+            }
+            @Override
+            public int getSupportLowerBound() {
+                return Integer.MIN_VALUE;
+            }
+            @Override
+            public int getSupportUpperBound() {
+                return 42;
+            }
+            @Override
+            public boolean isSupportConnected() {
+                return false;
+            }
+        };
+        Assertions.assertEquals(Integer.MIN_VALUE, dist.inverseCumulativeProbability(0.05));
+        Assertions.assertEquals(dist.getSupportUpperBound(), dist.inverseCumulativeProbability(1.0));
+    }
+
+    @Test
+    public void testInverseCumulativeProbabilityWithNaN() {
+        final DiscreteDistribution dist = new AbstractDiscreteDistribution() {
+            @Override
+            public double probability(int x) {
+                return 0;
+            }
+            @Override
+            public double cumulativeProbability(int x) {
+                // NaN is not allowed
+                return Double.NaN;
+            }
+            @Override
+            public double getMean() {
+                return 0;
+            }
+            @Override
+            public double getVariance() {
+                return 0;
+            }
+            @Override
+            public int getSupportLowerBound() {
+                return Integer.MIN_VALUE;
+            }
+            @Override
+            public int getSupportUpperBound() {
+                return Integer.MAX_VALUE;
+            }
+            @Override
+            public boolean isSupportConnected() {
+                return false;
+            }
+        };
+        Assertions.assertThrows(IllegalStateException.class, () -> dist.inverseCumulativeProbability(0.5));
+    }
+
     /**
      * Simple distribution modeling a 6-sided die
      */