test: Fix common.PIPE to be process unique

[refack]

• Fix common.PIPE to be process unique
• tiny bit of refactoring in adjacent lines

Fixes: #14128

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

test,stream,net

[lpinca]

Is block scoping really needed?

[refack]

Since the const are only used locally and there's a single exported side-effect (exports.PIPE = ...) IMHO it's cleaner.
Similar to the function setupFoo(); setupFoo(); approach in node_bootstap.js
Maybe even V8 will inline the consts ?

[gibfahn]

I like it, easier to see that the consts aren't used except in exports.PIPE.

[refack]

Not a huge fan of !! outside of minimal code competitions.
Willing to change if anyone has a strong opinion.

[Trott]

No strong opinion from me. I think it used to be preferred in hot paths for performance. No idea if that's still the case. Regardless, it's totally sensible to value readable code over performant code in test/common/index.js.

[refack]

Failures:

not ok 220 parallel/test-cluster-eaccess
  ---
  duration_ms: 0.218
  severity: fail
  stack: |-
    child listening
    child exiting
    PIPE should have been in use.
    master exited
    assert.js:48
      throw new errors.AssertionError({
      ^
    
    AssertionError [ERR_ASSERTION]: 'EADDRINUSE' === undefined
        at Worker.<anonymous> (/data/iojs/build/workspace/node-test-commit-linuxone/nodes/rhel72-s390x/test/parallel/test-cluster-eaccess.js:48:12)
        at Worker.<anonymous> (/data/iojs/build/workspace/node-test-commit-linuxone/nodes/rhel72-s390x/test/common/index.js:515:15)
        at emitTwo (events.js:130:20)
        at Worker.emit (events.js:213:7)
        at ChildProcess.Worker.process.on (internal/cluster/worker.js:28:12)
        at emitTwo (events.js:125:13)
        at ChildProcess.emit (events.js:213:7)
        at emit (internal/child_process.js:776:12)
        at _combinedTickCallback (internal/process/next_tick.js:141:11)
        at process._tickCallback (internal/process/next_tick.js:180:9)
  ...

not ok 1509 sequential/test-benchmark-http
  ---
  duration_ms: 3.632
  severity: fail
  stack: |-
    
    http/bench-parser.js
    http/bench-parser.js n=1 len=1: 10,362.694300518135
    
    http/check_invalid_header_char.js
    http/check_invalid_header_char.js n=1 key="\"\"": 9,291.521486643438
    
    http/check_is_http_token.js
    http/check_is_http_token.js n=1 key="\"\"": 9,632.797749778445
    
    http/chunked.js
    http/chunked.js c=1 len=1 n=1 benchmarker="test-double": 1
    
    http/client-request-body.js
    http/client-request-body.js method="write" len=1 type="asc" dur=0.1: 3,782.800838240719
    http/client-request-body.js method="end" len=1 type="asc" dur=0.1: 3,753.1900606189497
    http/client-request-body.js method="write" len=1 type="utf" dur=0.1: 4,350.617135040606
    http/client-request-body.js method="end" len=1 type="utf" dur=0.1: 4,771.837295122962
    http/client-request-body.js method="write" len=1 type="buf" dur=0.1: 4,070.584983768017
    http/client-request-body.js method="end" len=1 type="buf" dur=0.1: 4,119.2370015667975
    
    http/cluster.js
    http/cluster.js c=1 len=1 type="bytes" benchmarker="test-double": 1
    http/cluster.js c=1 len=1 type="buffer" benchmarker="test-double": 1
    
    http/create-clientrequest.js
    http/create-clientrequest.js n=1 len=1: 1,233.710396354139
    
    http/end-vs-write-end.js
    http/end-vs-write-end.js method="write" c=1 len=1 type="asc" benchmarker="test-double": 1
    http/end-vs-write-end.js method="end" c=1 len=1 type="asc" benchmarker="test-double": 1
    http/end-vs-write-end.js method="write" c=1 len=1 type="utf" benchmarker="test-double": 1
    http/end-vs-write-end.js method="end" c=1 len=1 type="utf" benchmarker="test-double": 1
    http/end-vs-write-end.js method="write" c=1 len=1 type="buf" benchmarker="test-double": 1
    http/end-vs-write-end.js method="end" c=1 len=1 type="buf" benchmarker="test-double": 1
    
    http/http_server_for_chunky_client.js
    events.js:182
          throw er; // Unhandled 'error' event
          ^
    
    Error: connect ENOENT /data/iojs/node-tmp/tmp.0/node-test.47355.sock
        at Object.exports._errnoException (util.js:1023:11)
        at exports._exceptionWithHostPort (util.js:1046:20)
        at PipeConnectWrap.afterConnect [as oncomplete] (net.js:1150:14)
    assert.js:48
      throw new errors.AssertionError({
      ^
    
    AssertionError [ERR_ASSERTION]: 1 === 0
        at ChildProcess.<anonymous> (/data/iojs/build/workspace/node-test-commit-linuxone/nodes/rhel72-s390x/benchmark/http/http_server_for_chunky_client.js:43:10)
        at emitTwo (events.js:125:13)
        at ChildProcess.emit (events.js:213:7)
        at maybeClose (internal/child_process.js:929:16)
        at Process.ChildProcess._handle.onexit (internal/child_process.js:212:5)
    assert.js:48
      throw new errors.AssertionError({
      ^
    
    AssertionError [ERR_ASSERTION]: 1 === 0
        at ChildProcess.child.on (/data/iojs/build/workspace/node-test-commit-linuxone/nodes/rhel72-s390x/test/sequential/test-benchmark-http.js:34:10)
        at emitTwo (events.js:125:13)
        at ChildProcess.emit (events.js:213:7)
        at Process.ChildProcess._handle.onexit (internal/child_process.js:201:12)
  ...

[gibfahn]

For the commit message, maybe:

test: make common.PIPE process unique

Also includes a tiny bit of refactoring in adjacent lines.

Fixes: https://github.com/nodejs/node/issues/14128

[refack]

CI: https://ci.nodejs.org/job/node-test-commit/11061/

[refack]

Known flakes:
smartOS - #14177
Windows - #14178

[refack]

Pre land CI: https://ci.nodejs.org/job/node-test-pull-request/9121/

[MylesBorins]

This does not land cleanly in LTS. Please feel free to manually backport by following the guide. Please also feel free to replace do-not-land if it is being backported