diff --git a/DIRECTORY.md b/DIRECTORY.md index 8d66f77d1ea9..398f61ec8442 100644 --- a/DIRECTORY.md +++ b/DIRECTORY.md @@ -945,6 +945,7 @@ * [DigitalRootTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DigitalRootTest.java) * [DistanceFormulaTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java) * [DudeneyNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DudeneyNumberTest.java) + * [EulerMethodTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/EulerMethodTest.java) * [EulersFunctionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/EulersFunctionTest.java) * [FactorialRecursionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FactorialRecursionTest.java) * [FactorialTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FactorialTest.java) diff --git a/src/test/java/com/thealgorithms/maths/EulerMethodTest.java b/src/test/java/com/thealgorithms/maths/EulerMethodTest.java new file mode 100644 index 000000000000..5ae5ac70b1df --- /dev/null +++ b/src/test/java/com/thealgorithms/maths/EulerMethodTest.java @@ -0,0 +1,79 @@ +package com.thealgorithms.maths; + +import static org.junit.jupiter.api.Assertions.assertArrayEquals; +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertThrows; + +import java.util.ArrayList; +import java.util.function.BiFunction; +import java.util.stream.Stream; +import org.junit.jupiter.params.ParameterizedTest; +import org.junit.jupiter.params.provider.Arguments; +import org.junit.jupiter.params.provider.MethodSource; + +class EulerMethodTest { + + private static class EulerFullTestCase { + double[] params; + BiFunction equation; + int expectedSize; + double[] expectedFirstPoint; + double[] expectedLastPoint; + + EulerFullTestCase(double[] params, BiFunction equation, int expectedSize, double[] expectedFirstPoint, double[] expectedLastPoint) { + this.params = params; + this.equation = equation; + this.expectedSize = expectedSize; + this.expectedFirstPoint = expectedFirstPoint; + this.expectedLastPoint = expectedLastPoint; + } + } + + @ParameterizedTest + @MethodSource("eulerStepTestCases") + void testEulerStep(double x, double h, double y, BiFunction equation, double expected) { + double result = EulerMethod.eulerStep(x, h, y, equation); + assertEquals(expected, result, 1e-9, "Euler step failed for the given equation."); + } + + static Stream eulerStepTestCases() { + return Stream.of(Arguments.of(0.0, 0.1, 1.0, (BiFunction) ((x, y) -> x + y), 1.1)); + } + + @ParameterizedTest + @MethodSource("eulerStepInvalidCases") + void testEulerStepInvalidInput(double x, double h, double y, BiFunction equation, Class expectedExceptionClass) { + assertThrows(expectedExceptionClass, () -> EulerMethod.eulerStep(x, h, y, equation)); + } + + static Stream eulerStepInvalidCases() { + BiFunction dummyEquation = (x, y) -> x + y; + return Stream.of(Arguments.of(0.0, -0.1, 1.0, dummyEquation, IllegalArgumentException.class), Arguments.of(0.0, 0.0, 1.0, dummyEquation, IllegalArgumentException.class)); + } + + @ParameterizedTest + @MethodSource("eulerFullTestCases") + void testEulerFull(EulerFullTestCase testCase) { + ArrayList result = EulerMethod.eulerFull(testCase.params[0], testCase.params[1], testCase.params[2], testCase.params[3], testCase.equation); + assertEquals(testCase.expectedSize, result.size(), "Incorrect number of points in the result."); + assertArrayEquals(testCase.expectedFirstPoint, result.get(0), 1e-9, "Incorrect first point."); + assertArrayEquals(testCase.expectedLastPoint, result.get(result.size() - 1), 1e-9, "Incorrect last point."); + } + + static Stream eulerFullTestCases() { + return Stream.of(Arguments.of(new EulerFullTestCase(new double[] {0.0, 1.0, 0.5, 0.0}, (x, y) -> x, 3, new double[] {0.0, 0.0}, new double[] {1.0, 0.25})), + Arguments.of(new EulerFullTestCase(new double[] {0.0, 1.0, 0.1, 1.0}, (x, y) -> y, 12, new double[] {0.0, 1.0}, new double[] {1.0999999999999999, 2.8531167061100002})), + Arguments.of(new EulerFullTestCase(new double[] {0.0, 0.1, 0.1, 1.0}, (x, y) -> x + y, 2, new double[] {0.0, 1.0}, new double[] {0.1, 1.1}))); + } + + @ParameterizedTest + @MethodSource("eulerFullInvalidCases") + void testEulerFullInvalidInput(double xStart, double xEnd, double stepSize, double yInitial, BiFunction equation, Class expectedExceptionClass) { + assertThrows(expectedExceptionClass, () -> EulerMethod.eulerFull(xStart, xEnd, stepSize, yInitial, equation)); + } + + static Stream eulerFullInvalidCases() { + BiFunction dummyEquation = (x, y) -> x + y; + return Stream.of(Arguments.of(1.0, 0.0, 0.1, 1.0, dummyEquation, IllegalArgumentException.class), Arguments.of(0.0, 1.0, 0.0, 1.0, dummyEquation, IllegalArgumentException.class), Arguments.of(0.0, 1.0, -0.1, 1.0, dummyEquation, IllegalArgumentException.class)); + } +}