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Update critical value for chi-square test (#1125)

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Alex Herbert 2023-10-20 22:23:01 +01:00 committed by GitHub
parent 29f3678bde
commit d82d465170
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1 changed files with 6 additions and 7 deletions
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src/test/java/org/apache/commons/lang3/RandomStringUtilsTest.java
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@ -435,7 +435,7 @@ public void testRandomPrintRange() {
/**
* Test homogeneity of random strings generated --
* i.e., test that characters show up with expected frequencies
* in generated strings. Will fail randomly about 1 in LOOP_COUNT times.
* in generated strings. Will fail randomly about 1 in 100,000 times.
* Repeated failures indicate a problem.
*/
@Test
@ -445,10 +445,7 @@ public void testRandomStringUtilsHomog() {
String gen = "";
final int[] counts = {0, 0, 0};
final int[] expected = {200, 200, 200};
// More likely to fail for 1000?
// Fails randomly too often when max is 100.
final int max = 90;
for (int i = 0; i < max; i++) {
for (int i = 0; i < 100; i++) {
gen = RandomStringUtils.random(6, chars);
for (int j = 0; j < 6; j++) {
switch (gen.charAt(j)) {
@ -470,8 +467,10 @@ public void testRandomStringUtilsHomog() {
}
}
}
// Perform chi-square test with df = 3-1 = 2, testing at .001 level
assertTrue(chiSquare(expected, counts) < 13.82, "test homogeneity -- will fail about 1 in 1000 times");
// Perform chi-square test with degrees of freedom = 3-1 = 2, testing at 1e-5 level.
// This expects a failure rate of 1 in 100,000.
// critical value: from scipy.stats import chi2; chi2(2).isf(1e-5)
assertTrue(chiSquare(expected, counts) < 23.025850929940457, "test homogeneity -- will fail about 1 in 100,000 times");
}
/**