This change removes `common.noop` from the Node.js internal testing
common module.

Over the last few weeks, I've grown to dislike the `common.noop`
abstraction.

First, new (and experienced) contributors are unaware of it and so it
results in a large number of low-value nits on PRs. It also increases
the number of things newcomers and infrequent contributors have to be
aware of to be effective on the project.

Second, it is confusing. Is it a singleton/property or a getter? Which
should be expected? This can lead to subtle and hard-to-find bugs. (To
my knowledge, none have landed on master. But I also think it's only a
matter of time.)

Third, the abstraction is low-value in my opinion. What does it really
get us? A case could me made that it is without value at all.

Lastly, and this is minor, but the abstraction is wordier than not using
the abstraction. `common.noop` doesn't save anything over `() => {}`.

So, I propose removing it.

PR-URL: https://github.com/nodejs/node/pull/12822
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>

Export a new common.noop no-operation function for general use.
Allow using common.mustCall() without a fn argument to simplify
test cases.

Replace various non-op functions throughout tests with common.noop

PR-URL: https://github.com/nodejs/node/pull/12027
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

* test: check invalid chunk error for readable.push

  Test that passing invalid chunks to readable.push() in
  non-object mode throw errors.

* test: add simple object mode + decoder stream test

* test: add test for readable stream lacking _read

  Check that using a readable stream without a _read method will throw
  an error.

* test: add basic test for piping to multiple dests

  Add a simple test for piping and unpiping from a readable stream
  to multiple writable streams.

PR-URL: https://github.com/nodejs/node/pull/7260
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>