cmd/go: avoid writing non-JSON "build failed" errors from 'go test -json'

In 'go test -json' we expect stdout to contain only JSON events,
not unstructured text. Unstructured text should either go to stderr
or be wrapped in a JSON event.

(If we add structured build output in #62067, we can emit this output
as a build event instead of a test event.)

Fixes #35169.
For #54378.

Change-Id: Ibedd28e79b5adf8d6ae56165b9f0393b14ece9aa
Reviewed-by: Austin Clements <>
Auto-Submit: Bryan Mills <>
LUCI-TryBot-Result: Go LUCI <>
2 files changed
tree: d9ffd5ef649be8e8ed9e7393decdd2a5ef8016b4
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg
  12. go.env

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