Build/Test Tools: Simplify redundant PHPUnit shim for setExpectedException().

PHPUnit 6 deprecated the `setExpectedException()` method in favor of the `expectException()`, `expectExceptionMessage()`, and `expectExceptionCode()` methods.

`WP_UnitTestCase_Base::setExpectedException()` backfilled the old method. As the PHPUnit Polyfills have a polyfill for the ''new'' method, this backfill can now be simplified.

This backfill ''should'' be removed in a future iteration, but is, for now, left in place so as not to break backward compatibility for plugin/theme test suites which extend the WP native test suite for their integration tests.

Follow-up to [48996], [48997], [51559-51561].

Props jrf.
See #46149.

git-svn-id: https://develop.svn.wordpress.org/trunk@51562 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

tests/phpunit/includes/abstract-testcase.php

@@ -564,23 +564,25 @@ public function setExpectedIncorrectUsage( $doing_it_wrong ) {
 	}
 
 	/**
-	 * PHPUnit 6+ compatibility shim.
+	 * Redundant PHPUnit 6+ compatibility shim. DO NOT USE!
+	 *
+	 * This method is only left in place for backward compatibility reasons.
+	 *
+	 * @deprecated 5.9.0 Use the PHPUnit native expectException*() methods directly.
 	 *
 	 * @param mixed      $exception
 	 * @param string     $message
 	 * @param int|string $code
 	 */
 	public function setExpectedException( $exception, $message = '', $code = null ) {
-		if ( method_exists( 'PHPUnit_Framework_TestCase', 'setExpectedException' ) ) {
-			parent::setExpectedException( $exception, $message, $code );
-		} else {
-			$this->expectException( $exception );
-			if ( '' !== $message ) {
-				$this->expectExceptionMessage( $message );
-			}
-			if ( null !== $code ) {
-				$this->expectExceptionCode( $code );
-			}
+		$this->expectException( $exception );
+
+		if ( '' !== $message ) {
+			$this->expectExceptionMessage( $message );
+		}
+
+		if ( null !== $code ) {
+			$this->expectExceptionCode( $code );
 		}
 	}