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Radar · Go · Archive · Week 11 · Mar 9 – 15, 2026

Annotate test output JSON with an “Error” flag

Worth knowingtooling

What changed
The proposal adds a boolean field “Error” to “output” actions in the JSON produced by cmd/test2json. This field is true for output produced via (*testing.T).Error{,f} and (*testing.T).Fatal{,f}, and for the first few lines of a crash (but not the stack trace).
Production impact
The source does not say.
Try it
Run go test -json on a package that uses t.Error and inspect the resulting JSON for the new “Error” field.
Source
github.com/golang/go/issues/62728

Understand it, then run it

The go test -json command turns test output into a stream of JSON objects. Until now, every line of output—whether it came from t.Log, t.Error, or a panic—looked the same. The change adds a new boolean field called Error to each JSON object that represents a line of output. If the line was produced by t.Error, t.Fatal, or the first few lines of a crash, Error is true; otherwise it is false. This lets tools know which lines are part of a test failure rather than just noise.

Written by gpt-oss-20b from the linked source · claims checked against the sources · archive, not individually reviewed