public function testNormalisePostCode()
 {
     $original = '1AA 2BB';
     $expected = strtolower(str_replace(' ', '', $original));
     $this->assertEmpty($this->instance->getPostcode());
     $this->assertEmpty($this->instance->getNormalisedPostcode());
     $this->assertInstanceOf(Authority::class, $this->instance->setPostcode($original));
     $this->assertEquals($original, $this->instance->getPostcode());
     $this->assertEquals($expected, $this->instance->getNormalisedPostcode());
 }