This patch makes protoio use the new protobuf API for
marshalling/unmarshalling text protobufs, as well as extends the tests
to cover marshalling failures.
The protobuf text output is not stable/deterministic and some spaces are
added randomly, so some integration tests have to be adjusted to account
for it.
This patch adds a new integration test to cover SPF checks. The main
goal is not to cover the SPF parsing, since that's handled by the
library already, but the higher level aspects: that the mails are indeed
rejected, that the DSN looks reasonable, etc.
The test/t-14-tls_tracking test relies on Go 1.8 features, but since we
used to support Go 1.7, the test had a version check.
Since now the minimum Go version supported is 1.9, we can remove this
check.
This patch adds a new test, which verifies the TLS tracking.
Because we need to simulate SPF records, and Go does not support fully
intercepting DNS lookups yet, this test relies on dnsmasq to provide a
DNS resolver.
In the future, once Go supports DNS lookup interception, we can get rid
of this additional dependency.
