Refactor ejer5 to avoid machers

Author: micaelgallego

tema1_2_ejer5/src/test/java/es/codeurjc/test/complex/ComplexTest.java

@@ -1,7 +1,5 @@
 package es.codeurjc.test.complex;
 
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.CoreMatchers.containsString;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
@@ -41,6 +39,6 @@ public void GivenComplex0_0_whenReciprocal_thenExceptionIsThrown() {
 		ArithmeticException actual = 
 				assertThrows(ArithmeticException.class, () -> zero.reciprocal());
 
-		assertThat(actual.getMessage(), containsString("division by zero"));
+		assertEquals(actual.getMessage(), "division by zero");
 	}
 }