refactor: change packages (#5430)

* refactor: change package

* refactor: fix name

---------

Co-authored-by: alxkm <alx@alx.com>

src/test/java/com/thealgorithms/maths/EulersFunctionTest.java

@@ -0,0 +1,33 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+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 EulersFunctionTest {
+
+    @ParameterizedTest
+    @MethodSource("provideNumbersForGetEuler")
+    void testGetEuler(int input, int expected) {
+        assertEquals(expected, EulersFunction.getEuler(input));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideInvalidNumbersForGetEuler")
+    void testGetEulerThrowsExceptionForNonPositiveInput(int input) {
+        assertThrows(IllegalArgumentException.class, () -> EulersFunction.getEuler(input));
+    }
+
+    private static Stream<Arguments> provideNumbersForGetEuler() {
+        return Stream.of(Arguments.of(1, 1), Arguments.of(2, 1), Arguments.of(3, 2), Arguments.of(4, 2), Arguments.of(5, 4), Arguments.of(6, 2), Arguments.of(10, 4), Arguments.of(21, 12), Arguments.of(69, 44), Arguments.of(47, 46), Arguments.of(46, 22), Arguments.of(55, 40), Arguments.of(34, 16),
+            Arguments.of(20, 8), Arguments.of(1024, 512));
+    }
+
+    private static Stream<Arguments> provideInvalidNumbersForGetEuler() {
+        return Stream.of(Arguments.of(0), Arguments.of(-1), Arguments.of(-10));
+    }
+}