fix(ws): fix incorrect host pattern on messages

[KrisAphalon]

function call was missing the second argument

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Currently, when using platform-ws and calling host.switchToWs().getPattern() on ArgumentsHost given in exception filter, we don't get a pattern but we get a data object. For example for following message on the websocket:

{
    event: 'foo',
    data: {  test: 1  }
}

we would get { test: 1 } as a "pattern"

Issue Number: N/A

What is the new behavior?

When using platform-ws and calling host.switchToWs().getPattern() on ArgumentsHost given in exception filter we get correct pattern matched for this branch. For the following message on the websocket:

{
    event: 'foo',
    data: {  test: 1  }
}

we correctly get 'foo' as a pattern

Does this PR introduce a breaking change?

• Yes
• No

Other information

If I traced the code correctly, currect behaviour happens because the code always gets the last item from the list as a pattern, but on platform-ws the message.event was never added to that list.

I'm not yet fluent with writing for libraries of this size and I didn't see any tests for platform-ws or for platform-socket.io. That's why I didn't add a test myself. I did see there were some tests for getPattern(), but none of them caught this problem. Probably because they were more high-level than the change here.

[coveralls]

Pull Request Test Coverage Report for Build 01d7bc0e-3eb7-47ff-ab0e-8865252cdc2d

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.61%

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Totals
Change from base Build ac9c1c51-3db3-4328-86ea-d3cf5d1cde0c:	0.0%
Covered Lines:	6466
Relevant Lines:	6982

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💛 - Coveralls

[kamilmysliwiec]

Could you please provide a minimum reproduction repository (Git repository/StackBlitz/CodeSandbox project)?

[KrisAphalon]

Right. I think this is sufficient: https://github.com/KrisAphalon/nestjs-incorrect-host-pattern-example
Not sure if it can cut more corners with it. The gist of it is I throw exception in a method in a gateway (or in real code in some service called within it) and the custom WebsocketExceptionFilter catches it. Within the filter I call host.switchToWs().getPattern() and get an incorrect variable.

[kamilmysliwiec]

cc @jmcdo29 (added in #10545)

[jmcdo29]

Nice catch. I can confirm with my external library that there was indeed a bug with this, and the proposed changes do fix it

[kamilmysliwiec]

LGTM