[GitHub] [commons-statistics] kinow commented on a diff in pull request #49: [STATISTICS-76]: Max Implementation

["kinow (via GitHub)" <gi...@apache.org>]

kinow commented on code in PR #49:
URL: https://github.com/apache/commons-statistics/pull/49#discussion_r1264731414


##########
commons-statistics-descriptive/src/test/java/org/apache/commons/statistics/descriptive/MaxTest.java:
##########
@@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.statistics.descriptive;
+
+import java.util.Arrays;
+import java.util.function.DoubleSupplier;
+import java.util.stream.Stream;
+import org.apache.commons.rng.UniformRandomProvider;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+/**
+ * Test for {@link Max}.
+ */
+final class MaxTest {
+
+    @Test
+    void testEmpty() {
+        Max max = Max.create();
+        Assertions.assertEquals(Double.NEGATIVE_INFINITY, max.getAsDouble());
+    }
+
+    @Test
+    void testIncrement() {
+        // Test the max after each incremental update
+        // First parameter of testArray is the value that would be added
+        // Second parameter of testArray is the max we expect after adding the value
+        double[][] testArray = {
+            {1729.22, 1729.22},
+            {2520.35, 2520.35},
+            {2010.87, 2520.35},
+            {100000000.1, 100000000.1},
+            {+0.0, 100000000.1},
+            {-0.0, 100000000.1},
+            {Double.MAX_VALUE, Double.MAX_VALUE},
+            {Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY},
+            {Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY}
+        };
+
+        Max stat = Max.create();
+        for (final double[] valueAndExpected: testArray) {
+            final double value = valueAndExpected[0];
+            final double expected = valueAndExpected[1];
+            stat.accept(value);
+            Assertions.assertEquals(expected, stat.getAsDouble());
+        }
+    }
+
+    @Test
+    void testNaN() {
+        // Test non-nan values cannot revert a NaN
+        double[] testArray = {Double.NaN, +0.0d, -0.0d, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY};
+        Max stat = Max.create();
+        for (final double x : testArray) {
+            stat.accept(x);
+            Assertions.assertEquals(Double.NaN, stat.getAsDouble());
+        }
+    }
+
+    @ParameterizedTest
+    @MethodSource
+    void testMax(double[] values, double expected) {
+        Max stat = Max.create();
+        Arrays.stream(values).forEach(stat);
+        double actual = stat.getAsDouble();
+        Assertions.assertEquals(expected, actual, "max");
+        Assertions.assertEquals(expected, Max.of(values).getAsDouble(), "max");
+    }
+
+    static Stream<Arguments> testMax() {
+        return Stream.of(
+            Arguments.of(new double[] {}, Double.NEGATIVE_INFINITY),
+            Arguments.of(new double[] {3.14}, 3.14),
+            Arguments.of(new double[] {12.34, 56.78, -2.0}, 56.78),
+            Arguments.of(new double[] {Double.NaN, 3.14, Double.NaN, Double.NaN}, Double.NaN),
+            Arguments.of(new double[] {-1d, 1d, Double.NaN}, Double.NaN),
+            Arguments.of(new double[] {Double.NaN, Double.NaN, Double.NaN}, Double.NaN),
+            Arguments.of(new double[] {0.0d, Double.NaN, +0.0d, -0.0d, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY}, Double.NaN),
+            Arguments.of(new double[] {+0.0d, -0.0d, 1.0, 3.14}, 3.14),
+            Arguments.of(new double[] {-0.0, +0.0}, 0.0),
+            Arguments.of(new double[] {0.0, -0.0}, 0.0),
+            Arguments.of(new double[] {0.0, +0.0}, 0.0),
+            Arguments.of(new double[] {1.2, -34.56, 456.789, -5678.9012}, 456.789),
+            Arguments.of(new double[] {-23467824, 23648, 2368, 23749, -23424, -23492, -92397747}, 23749),
+            Arguments.of(new double[] {0.0d, +0.0d, -0.0d, Double.POSITIVE_INFINITY, Double.MIN_VALUE}, Double.POSITIVE_INFINITY),
+            Arguments.of(new double[] {0.0d, +0.0d, -0.0d, Double.POSITIVE_INFINITY, -Double.MIN_VALUE}, Double.POSITIVE_INFINITY),
+            Arguments.of(new double[] {0.0d, +0.0d, -0.0d, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY, Double.MIN_VALUE}, Double.POSITIVE_INFINITY)

Review Comment:
   Quickly compared the code in this PR with the existing Min code, and everything looks OK. The only part I noticed that did not change was this with the `Double.MIN_VALUE`'s. Is that intentional or were we supposed to use `Double.MAX_VALUE` for this test?



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