SpannerIO tests don't actually assert anything.

[damccorm]

These all have the format

p = Pipeline()
...
p.run()
assert_that(...)

Imported from Jira BEAM-10569. Original Jira may contain additional context.
Reported by: robertwb.

[Abacn]

There is a cross-language spanner io (apache_beam.io.gcp.spanner) and this native implementation is less actively supported and may be deprecated in the future. May decrease the priority of this issue.