mojo/public/tools/mojom/version_compatibility_unittest.py
def testNewUnionFieldWithValidMinVersion(self):
    """Adding a new field is safe if tagged with a MinVersion greater than any
    previously used MinVersion in the union."""
    self.assertBackwardCompatible(
        'union U { int32 a; };',
        'union U { int32 a; [MinVersion=1] int32 b; };')
    self.assertBackwardCompatible(
        'union U { int32 a; [MinVersion=1] int32 b; };',
        'union U { int32 a; [MinVersion=1] int32 b; [MinVersion=2] bool c; };')
Adding a new field is safe if tagged with a MinVersion greater than any
    previously used MinVersion in the union.
Adding a new field is safe if tagged with a MinVersion greater than any
previously used MinVersion in the union.
Adding a new field is safe if tagged with a MinVersion greater than any previously used MinVersion in the union .
def testNewUnionFieldWithValidMinVersion(self):
    self.assertBackwardCompatible(
        'union U { int32 a; };',
        'union U { int32 a; [MinVersion=1] int32 b; };')
    self.assertBackwardCompatible(
        'union U { int32 a; [MinVersion=1] int32 b; };',
        'union U { int32 a; [MinVersion=1] int32 b; [MinVersion=2] bool c; };')
def testNewUnionFieldWithValidMinVersion ( self ) : self . assertBackwardCompatible ( 'union U { int32 a; };' , 'union U { int32 a; [MinVersion=1] int32 b; };' ) self . assertBackwardCompatible ( 'union U { int32 a; [MinVersion=1] int32 b; };' , 'union U { int32 a; [MinVersion=1] int32 b; [MinVersion=2] bool c; };' )
Adding a new field is safe if tagged with a MinVersion greater than any
previously used MinVersion in the union.
Adding a new field is safe if tagged with a MinVersion greater than any previously used MinVersion in the union .
"""Adding a new field is safe if tagged with a MinVersion greater than any
    previously used MinVersion in the union."""
self