Add a new test capturing the new expectation. · python/importlib

Add a new test capturing the new expectation. · python/importlib_metadata@e4351c2

Original file line number	Diff line number	Diff line change
`@@ -155,6 +155,16 @@ def test_valid_dists_preferred(self):`
`155`	`155`	`dist = Distribution.from_name('foo')`
`156`	`156`	`assert dist.version == "1.0"`
`157`	`157`
	`158`	`+def test_missing_metadata(self):`
	`159`	`+"""`
	`160`	`+ Dists with a missing metadata file should return None.`
	`161`	`+`
	`162`	`+ Ref python/importlib_metadata#493.`
	`163`	`+ """`
	`164`	`+fixtures.build_files(self.make_pkg('foo-4.3', files={}), self.site_dir)`
	`165`	`+assert Distribution.from_name('foo').metadata is None`
	`166`	`+assert metadata('foo') is None`
	`167`	`+`
`158`	`168`
`159`	`169`	`class NonASCIITests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):`
`160`	`170`	`@staticmethod`