Add tests for use_output_buffer

tests/server-timing/perflab-server-timing-tests.php

@@ -187,10 +187,56 @@ public function data_get_header() {
 		);
 	}
 
-	public function test_use_output_buffer() {
-		$this->assertFalse( $this->server_timing->use_output_buffer() );
+	public function get_data_to_test_use_output_buffer() {
+		$enable_option = static function () {
+			$option = (array) get_option( PERFLAB_SERVER_TIMING_SETTING );
+			$option['output_buffering'] = true;
+			update_option( PERFLAB_SERVER_TIMING_SETTING, $option );
+		};
+		$disable_option = static function () {
+			$option = (array) get_option( PERFLAB_SERVER_TIMING_SETTING );
+			$option['output_buffering'] = false;
+			update_option( PERFLAB_SERVER_TIMING_SETTING, $option );
+		};
 
-		add_filter( 'perflab_server_timing_use_output_buffer', '__return_true' );
-		$this->assertTrue( $this->server_timing->use_output_buffer() );
+		return array(
+			'default' => array(
+				'set_up'   => static function () {},
+				'expected' => false,
+			),
+			'option-enabled' => array(
+				'set_up'   => $enable_option,
+				'expected' => true,
+			),
+			'option-disabled' => array(
+				'set_up'   => $disable_option,
+				'expected' => false,
+			),
+			'filter-enabled' => array(
+				'set_up'   => static function () use ( $disable_option ) {
+					$disable_option();
+					add_filter( 'perflab_server_timing_use_output_buffer', '__return_true' );
+				},
+				'expected' => true,
+			),
+			'filter-disabled' => array(
+				'set_up'   => static function () use ( $enable_option ) {
+					$enable_option();
+					add_filter( 'perflab_server_timing_use_output_buffer', '__return_false' );
+				},
+				'expected' => false,
+			),
+		);
+	}
+
+	/**
+	 * @covers Perflab_Server_Timing::use_output_buffer
+	 * @dataProvider get_data_to_test_use_output_buffer
+	 * @param callable $set_up   Set up.
+	 * @param bool     $expected Expected value.
+	 */
+	public function test_use_output_buffer( callable $set_up, $expected ) {
+		$set_up();
+		$this->assertSame( $expected, $this->server_timing->use_output_buffer() );
 	}
 }