cmd/nm: short tests are not short enough

[rsc]

Running all.bash (which does go test -short std cmd), my target is usually that individual tests should run in under 1 second.

The cmd/nm test takes 6.4s on my system, which seems crazy. Can we make it take less time? If it's compiling a binary to run nm on, it seems like it would work fine to use any existing binary, like $GOROOT/bin/go.

/cc @aclements

[shivakumargn]

On my system (linux/amd64) it runs in 1.677s. Am I missing something?

> go test cmd/nm -v
=== RUN   TestInternalLinkerCgoExec
--- PASS: TestInternalLinkerCgoExec (0.35s)
=== RUN   TestExternalLinkerCgoExec
--- PASS: TestExternalLinkerCgoExec (0.46s)
=== RUN   TestCgoLib
--- PASS: TestCgoLib (0.18s)
=== RUN   TestNonGoExecs
--- PASS: TestNonGoExecs (0.02s)
=== RUN   TestGoExec
--- PASS: TestGoExec (0.24s)
=== RUN   TestGoLib
--- PASS: TestGoLib (0.02s)
PASS
ok  	cmd/nm	1.677s

[ysmolski]

Just tested tip on my slow Mac:

~/golang/src (master $=) % go test cmd/nm -v -short
=== RUN   TestInternalLinkerCgoExec
--- PASS: TestInternalLinkerCgoExec (0.57s)
=== RUN   TestExternalLinkerCgoExec
--- PASS: TestExternalLinkerCgoExec (0.87s)
=== RUN   TestCgoLib
--- PASS: TestCgoLib (0.38s)
=== RUN   TestNonGoExecs
--- PASS: TestNonGoExecs (0.04s)
=== RUN   TestGoExec
--- PASS: TestGoExec (0.33s)
=== RUN   TestGoLib
--- PASS: TestGoLib (0.04s)
PASS
ok  	cmd/nm	2.716s

What target time are we trying to achieve?

[gopherbot]

Change https://golang.org/cl/153499 mentions this issue: cmd/nm: run tests in parallel, don't use Scanner on []byte