Go Test Failures in CI - Read FAIL Output and Exit Code 1

go test exits non-zero when a test reports a failure. Exit code 1 with --- FAIL lines is a genuine assertion failure - the code under test behaved differently than the test expected.

What this error means

go test ./... prints one or more --- FAIL: TestName blocks with the failing assertion and ends with FAIL and exit code 1. The failing test names and messages point straight at the problem.

go test output

--- FAIL: TestSum (0.00s)
    sum_test.go:14: Sum(2, 3) = 6; want 5
FAIL
exit status 1
FAIL	github.com/yourorg/app/math	0.012s

Common causes

A real behavior change or bug

The code under test returns something the assertion does not expect - a genuine regression or a test that needs updating to match intended new behavior.

Environment-dependent assertions

A test that depends on time zone, locale, ordering, or filesystem layout can fail in CI while passing locally because the environment differs.

How to fix it

Read the failing assertion and reproduce it

Run just the failing test verbosely to see the exact got/want.

Terminal

go test -run TestSum -v ./math/...

Fix the code or the expectation

If the code is wrong, fix it so the assertion passes.
If the test encodes an outdated expectation, update the expected value deliberately.
For environment-dependent failures, make the test hermetic (inject the clock, fix the locale, sort before comparing).

How to prevent it

Keep tests hermetic and independent of host time zone, locale, and ordering.
Run go test ./... locally before pushing.
Treat a --- FAIL as a real signal, not flake, until proven otherwise.