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testing: improving test coverage CountingInversionsTest (#6393)

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testing: improving test coverage CountingInversionsTest

Co-authored-by: Deniz Altunkapan <93663085+DenizAltunkapan@users.noreply.github.com>
This commit is contained in:
Oleksandr Klymenko
2025-07-18 22:29:16 +03:00
committed by GitHub
parent 44c572b36b
commit fc477ee8da
1 changed files with 31 additions and 0 deletions
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31
src/test/java/com/thealgorithms/divideandconquer/CountingInversionsTest.java
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@@ -29,4 +29,35 @@ public class CountingInversionsTest {
int[] arr = {5, 4, 3, 2, 1};
assertEquals(10, CountingInversions.countInversions(arr));
}
@Test
public void testEmptyArray() {
int[] arr = {};
assertEquals(0, CountingInversions.countInversions(arr));
}
@Test
public void testArrayWithDuplicates() {
int[] arr = {1, 3, 2, 3, 1};
// Inversions: (3,2), (3,1), (3,1), (2,1)
assertEquals(4, CountingInversions.countInversions(arr));
}
@Test
public void testLargeArray() {
int n = 1000;
int[] arr = new int[n];
for (int i = 0; i < n; i++) {
arr[i] = n - i; // descending order -> max inversions = n*(n-1)/2
}
int expected = n * (n - 1) / 2;
assertEquals(expected, CountingInversions.countInversions(arr));
}
@Test
public void testArrayWithAllSameElements() {
int[] arr = {7, 7, 7, 7};
// No inversions since all elements are equal
assertEquals(0, CountingInversions.countInversions(arr));
}
}