[commons-statistics] 18/35: Increase GumbelDistribution 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 a1bd094c10cfd2adde352b7dc1131aaa05c8ba36
Author: aherbert <ah...@apache.org>
AuthorDate: Tue Jun 23 14:56:52 2020 +0100

    Increase GumbelDistribution test coverage.
---
 .../distribution/GumbelDistributionTest.java       | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/GumbelDistributionTest.java b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/GumbelDistributionTest.java
index f0bcf73..fb49112 100644
--- a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/GumbelDistributionTest.java
+++ b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/GumbelDistributionTest.java
@@ -67,4 +67,32 @@ public class GumbelDistributionTest extends ContinuousDistributionAbstractTest {
             4.589561e-01, 6.235249e-01, 7.508835e-01, 8.404869e-01, 8.999652e-01
         };
     }
+
+    // ----------------- Additional test cases ---------------------------------
+
+    @Test
+    public void testInverseCumulativeProbabilityExtremes() {
+        setInverseCumulativeTestPoints(new double[] {0.0, 1.0});
+        setInverseCumulativeTestValues(new double[] {Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY});
+        verifyInverseCumulativeProbabilities();
+    }
+
+    @Test
+    public void testConstructorPrecondition1() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> new GumbelDistribution(10, -0.1));
+    }
+
+    @Test
+    public void testMoments() {
+        final double tol = 1e-9;
+        GumbelDistribution dist;
+
+        dist = new GumbelDistribution(10, 0.5);
+        Assertions.assertEquals(10 + (Math.PI / (2 * Math.E)) * 0.5, dist.getMean(), tol);
+        Assertions.assertEquals((Math.PI * Math.PI / 6) * 0.5 * 0.5, dist.getVariance(), tol);
+
+        dist = new GumbelDistribution(30, 0.3);
+        Assertions.assertEquals(30 + (Math.PI / (2 * Math.E)) * 0.3, dist.getMean(), tol);
+        Assertions.assertEquals((Math.PI * Math.PI / 6) * 0.3 * 0.3, dist.getVariance(), tol);
+    }
 }