test: add hijackStdout and hijackStderr #13439

XadillaX · 2017-06-03T17:31:31Z

Add common.hijackStdout and common.hijackStderr to provide monitor
for console output.

Refs:

node/test/parallel/test-global-console-exists.js

Lines 41 to 43 in 917f86e

    
           // TODO: Figure out how to validate console. Currently, 
        
           // there is no obvious way of validating that console 
        
           // exists here exactly when it should.

Checklist

make -j4 test (UNIX)
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. Refs: https://github.com/nodejs/node/blob/917f86ea353e087af3bc4553219ffabaa2193d20/test/parallel/test-global-console-exists.js#L41-L43

XadillaX · 2017-06-03T17:55:26Z

/cc @nodejs/testing

gibfahn · 2017-06-03T17:58:50Z

cc/ @nodejs/testing

mscdex · 2017-06-03T19:58:54Z

Why is this being added to the test/common.js for a single test? It seems like this is very test-specific and should belong in the test file itself?

refack · 2017-06-03T20:13:10Z

Why is this being added to the test/common.js for a single test? It seems like this is very test-specific and should belong in the test file itself?

I'm with @mscdex.
@XadillaX I think best course of action is to lower hijackStdout and hijackStderr into the test, and open a second PR for hoisting them to common (My estimation: some non trivial push back, e.g. #13346 (comment), #12935)

gibfahn · 2017-06-03T20:46:52Z

and open a second PR for hoisting them to common

Better yet, hoist them to common if it turns out there's a need for them in several tests.

gireeshpunathil · 2017-06-04T05:34:41Z

test/common/index.js

+  stream.write = function(data) {
+    listener(data);
+    _write(data);
+    stream.writeTimes++;


This logic seem not go well with the writable.write specification:

callback (Function) :Callback for when this chunk of data is flushed

Your logic will cause:

Issue the completion handler before the actual write (_write)

Listener will be called in the same loop tick, making it a direct call, not a callback.

I propose:
_wite(data, listener)

In fact, listener is something like .emit('write') but not .emit('written'), so it's sync.

And I've added the callback in _write now.

XadillaX · 2017-06-04T07:30:57Z

@gibfahn @mscdex @refack I've found out some other situations to use these functions and updated the code.

mscdex · 2017-06-04T07:43:10Z

test/parallel/test-process-raw-debug.js

-  stderr.write = function() {
-    throw new Error('No writing to stderr!');
-  };
+  common.hijackStderr(common.mustNotCall('stderr.write mustn\'t be called.'));


I'd avoid the contraction or use template strings.

sorry, I don't quite understand what's your meaning

Replace 'stderr.write mustn\'t be called.' with either:

'stderr.write must not be called.'
or

`stderr.write mustn't be called.`

thefourtheye · 2017-06-04T11:12:51Z

test/common/README.md

@@ -116,6 +116,16 @@ Checks whether `IPv6` is supported on this platform.

 Checks if there are multiple localhosts available.

+### hijackStderr(listener)
+* `listener` [&lt;Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Normal_objects_and_functions): An listener with a single parameter called `data`;


"A listener"

Also, please break the lines at 80 chars if possible.

thefourtheye · 2017-06-04T11:15:21Z

test/fixtures/echo-close-check.js

+
+let current;
+common.hijackStdout(function(data) {
+  assert.equal(data, current);


Please use strict equal.

thefourtheye · 2017-06-04T11:16:02Z

test/fixtures/echo-close-check.js

+const stdin = process.openStdin();
+
+let current;
+common.hijackStdout(function(data) {


As there is an assertion in the listener function, it is better to have it wrapped in common.mustCall

thefourtheye · 2017-06-04T11:16:39Z

test/parallel/test-console.js

@@ -159,3 +156,13 @@ assert.throws(() => {
 assert.doesNotThrow(() => {
  console.assert(true, 'this should not throw');
 });
+
+// hijack stderr to catch `process.emitWarning` which using `process.nextTick`


which is using

thefourtheye · 2017-06-04T11:17:04Z

test/parallel/test-global-console-exists.js


-let write_calls = 0;
+common.hijackStderr(function(data) {


common.mustCall

refack

Some nits
Some comments about synchronization
I'm +1 for this feature

refack · 2017-06-04T16:28:15Z

test/parallel/test-console.js

+
+  // stderr.write will catch sync error, so use `process.nextTick` here
+  process.nextTick(function() {
+    assert(/no such label/.test(data));


I like assert.strictEqual(data.includes('no such label'), true) better

refack · 2017-06-04T16:33:42Z

test/common/README.md

@@ -116,6 +116,26 @@ Checks whether `IPv6` is supported on this platform.

 Checks if there are multiple localhosts available.

+### hijackStderr(listener)
+* `listener`
+[&lt;Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Normal_objects_and_functions):


(I know everywhere else uses it this way but) if you are using this link more than one you could use [MDN-Function][], and put

[MDN-Function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Normal_objects_and_functions

the the bottom of the file.

refack · 2017-06-04T16:34:19Z

test/common/README.md

+[&lt;Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Normal_objects_and_functions):
+a listener with a single parameter called `data`.
+
+Hijack `process.stderr` to listen `write` action. Once `process.stderr.write` is


Hijack `process.stderr` to listen `write` action => Eavesdrop to `process.stderr.write` calls

refack · 2017-06-04T16:37:44Z

test/common/README.md

+
+Hijack `process.stderr` to listen `write` action. Once `process.stderr.write` is
+called, `listener` will also be called and the `data` of `write` function will
+be passed to `listener`. What's more, `process.stderr.writeTimes` will plus one


... `process.stderr.writeTimes` is a count of the number of calls

refack · 2017-06-04T16:39:48Z

test/common/README.md

+[&lt;Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Normal_objects_and_functions):
+a listener with a single parameter called `data`.
+
+Hijack `process.stdout` to listen `write` action. Once `process.stdout.write` is


Same as above.

IMHO since this is an "internal" guide you could merge then into
### hijackStdout/Stderr(listener)

refack · 2017-06-04T16:45:04Z

test/fixtures/echo-close-check.js

+const stdin = process.openStdin();
+
+let current;
+common.hijackStdout(common.mustCall(function(data) {


I don't this this is an interesting use of hijackStdout, it just tests the mechanics of hijackStdout.
BTW: you should do that in explicitly in test/parallel/test-common.js

refack · 2017-06-04T16:45:18Z

test/fixtures/echo.js

  process.stdout.write(data.toString());
 });
+
+common.hijackStdout(function(data) {


refack · 2017-06-04T16:48:53Z

test/parallel/test-console.js

@@ -105,8 +103,10 @@ console.timeEnd('constructor');
 console.time('hasOwnProperty');
 console.timeEnd('hasOwnProperty');

-global.process.stdout.write = stdout_write;
-global.process.stderr.write = stderr_write;
+assert.strictEqual(strings.length, process.stdout.writeTimes);


won't this fail after you implemented @gireeshpunathil's async comment?

In fact, listener is sync which means a write action is emitted but not finished.

I just added the callback to the original _write function to make it may receivecallback.

refack · 2017-06-04T16:51:19Z

test/parallel/test-console.js

@@ -146,9 +146,6 @@ assert.ok(/^hasOwnProperty: \d+\.\d{3}ms$/.test(strings.shift().trim()));
 assert.strictEqual('Trace: This is a {"formatted":"trace"} 10 foo',
                   errStrings.shift().split('\n').shift());

-assert.strictEqual(strings.length, 0);


Keep this.
But I assume you'll need to solve async issues with this whole block.

Same which mentioned before.

And assert.strictEqual(strings.length, 0) equals above assert.strictEqual(strings.length, process.stdout.writeTimes);.

refack · 2017-06-04T16:53:43Z

Quick CI (linuxone): https://ci.nodejs.org/job/node-test-commit-linuxone/6370/

refack

Thanks ✔️

refack · 2017-06-05T04:40:58Z

CI: https://ci.nodejs.org/job/node-test-commit/10358/

XadillaX · 2017-06-05T08:56:43Z

@refack Thanks

jasnell · 2017-06-05T18:06:19Z

test/common/README.md

@@ -116,6 +116,14 @@ Checks whether `IPv6` is supported on this platform.

 Checks if there are multiple localhosts available.

+### hijackStderr/Stdout(listener)


These should be listed as separate functions (even if it means duplicating the text)

@jasnell I suggested the the merge (since it's an internal guide) #13439 (comment)
Please 👍 / 👎 again, just so we don't ask @XadillaX to do unnecessary work

I'd rather keep the style consistent throughout, so would really prefer them separate.

Ack.
Sorry @XadillaX

jasnell · 2017-06-05T18:06:57Z

test/common/README.md

@@ -250,6 +258,14 @@ Port tests are running on.

 Deletes the 'tmp' dir and recreates it

+### restoreStderr


If these are functions, then please include the ()

refack · 2017-06-05T22:18:47Z

@Trott you ok with this?

Trott · 2017-06-06T04:15:08Z

@Trott you ok with this?

I'm neutral on this change, so I guess that means I'm ok with it.

XadillaX · 2017-06-08T06:08:20Z

I think I've done all of the work after reviewing. @jasnell

DavidCai1111 · 2017-06-08T06:15:42Z

CI++: https://ci.nodejs.org/job/node-test-pull-request/8549/

refack · 2017-06-08T13:49:52Z

/cc @nodejs/testing anyone else have an 👍 / 👎 opinion?

XadillaX · 2017-06-09T14:07:59Z

so could it be landed now?

Trott · 2017-06-09T17:00:09Z

so could it be landed now?

If CI failures are unrelated (I haven't looked), then, yes, this can be landed. Probable lander would be @refack since he's the sole approval right now.

@mscdex @gibfahn If you're questions/skepticism should be interpreted as being opposed to this landing, please say so and maybe use the request changes review option.

refack · 2017-06-09T17:08:33Z

so could it be landed now?

@XadillaX technically it's ready, AFAICT CI is clean, but hust in case:
rerun arm: https://ci.nodejs.org/job/node-test-commit-arm-fanned/9322/
rerun AIX: https://ci.nodejs.org/job/node-test-commit-aix/6481/

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. PR-URL: nodejs#13439 Reviewed-By: Refael Ackermann <refack@gmail.com>

refack · 2017-06-09T17:58:26Z

Landed in d00e5f1

refack · 2017-06-09T17:59:10Z

Extra quick sanity of master: https://ci.nodejs.org/job/node-test-commit-linuxone/6518/

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. PR-URL: #13439 Reviewed-By: Refael Ackermann <refack@gmail.com>

MylesBorins · 2017-07-17T18:03:24Z

is this something we want to add to lts?

MylesBorins · 2017-08-14T18:57:03Z

if we want to land this on 6.x it will require a manual backport

test: add hijackStdout and hijackStderr

82dd2c2

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. Refs: https://github.com/nodejs/node/blob/917f86ea353e087af3bc4553219ffabaa2193d20/test/parallel/test-global-console-exists.js#L41-L43

nodejs-github-bot added the test Issues and PRs related to the tests. label Jun 3, 2017

gireeshpunathil reviewed Jun 4, 2017

View reviewed changes

mscdex added events Issues and PRs related to the events subsystem / EventEmitter. process Issues and PRs related to the process subsystem. labels Jun 4, 2017

update after reviewing

d261893

mscdex reviewed Jun 4, 2017

View reviewed changes

gibfahn requested a review from Trott June 4, 2017 10:33

expand contraction

bda1fd1

thefourtheye reviewed Jun 4, 2017

View reviewed changes

update after @thefourtheye's reviewing

5a3a666

refack approved these changes Jun 4, 2017

View reviewed changes

update after @refack's reviewing

ab93f52

refack approved these changes Jun 5, 2017

View reviewed changes

jasnell reviewed Jun 5, 2017

View reviewed changes

refack self-assigned this Jun 6, 2017

update afeter @jasnell's reviewing

2a42456

refack pushed a commit to refack/node that referenced this pull request Jun 9, 2017

test: add hijackStdout and hijackStderr

d00e5f1

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. PR-URL: nodejs#13439 Reviewed-By: Refael Ackermann <refack@gmail.com>

refack closed this Jun 9, 2017

addaleax pushed a commit that referenced this pull request Jun 10, 2017

test: add hijackStdout and hijackStderr

bdbeb33

Add `common.hijackStdout` and `common.hijackStderr` to provide monitor for console output. PR-URL: #13439 Reviewed-By: Refael Ackermann <refack@gmail.com>

addaleax mentioned this pull request Jun 10, 2017

v8.1.1 proposal #13598

Merged

gibfahn mentioned this pull request Jun 15, 2017

Auditing for 6.11.1 nodejs/Release#230

Closed

3 tasks

MylesBorins added the lts-watch-v6.x label Jul 17, 2017

MylesBorins added backport-requested-v6.x and removed lts-watch-v6.x labels Aug 14, 2017

This was referenced Aug 23, 2018

test: move hijackstdio out of require('common') #22462

Closed

test: help annotate test/parallel/test-util-log.js #22472

Closed

refack removed their assignment Oct 20, 2018

	// TODO: Figure out how to validate console. Currently,
	// there is no obvious way of validating that console
	// exists here exactly when it should.

		@@ -116,6 +116,14 @@ Checks whether `IPv6` is supported on this platform.

		Checks if there are multiple localhosts available.

		### hijackStderr/Stdout(listener)

		@@ -250,6 +258,14 @@ Port tests are running on.

		Deletes the 'tmp' dir and recreates it

		### restoreStderr


		let write_calls = 0;
		common.hijackStderr(function(data) {

test: add hijackStdout and hijackStderr #13439

test: add hijackStdout and hijackStderr #13439

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