Delete Content-Type header for multipart requests

[gydroperit]

We need to delete Content-Type header every time we create new instance of Request to properly set boundary in headers and in body.
Fixes #209

[sindresorhus]

// @rangermeier

[rangermeier]

Not sure if it's a good idea to always remove Content-Type header for multipart requests. As discussed in #204 (comment) there might be need for setting the content-type when sending multipart.

I think it would be safer to move the new code into its preceding if() statement:

		if (this._options.searchParams) {
			const url = new URL(this.request.url);
			url.search = new URLSearchParams(this._options.searchParams);

			if (((supportsFormData && this._options.body instanceof globals.FormData) || this._options.body instanceof URLSearchParams) && this.request.headers.has('content-type')) {
				this.request.headers.delete('content-type');
			}

			this.request = new globals.Request(new globals.Request(url, this.request), this._options);
		}

[sholladay]

I think it would be safer to move the new code into its preceding if() statement:

Agreed. At the end of the day, this is a hack, and thus the scope of its impact should be reduced as much as possible so it only takes effect when really necessary. I also think it's worth leaving a code comment here describing why it's being done, perhaps with a link to the original problem.

[sindresorhus]

@gydroperit Ping :)

[sindresorhus]

Tests are failing

[gydroperit]

Added test cases for request with FormData and searchParams and custom content-type header.
But this

ky/test/browser.js

Line 207 in 041e935

test.failing('FormData with searchParams ("multipart/form-data" parser)', withPage, async (t, page) => {

test case fails because of some strange puppeteer error

 browser › FormData with searchParams ("multipart/form-data" parser)

  node_modules/puppeteer/lib/Connection.js:74

  Rejected promise returned by test. Reason:

  Error {
    message: 'Protocol error (Target.closeTarget): Target closed.',
  }

  node_modules/puppeteer/lib/Connection.js:74:56
  Connection.send (node_modules/puppeteer/lib/Connection.js:73:12)
  Page.close (node_modules/puppeteer/lib/Page.js:1040:38)
  Page.<anonymous> (node_modules/puppeteer/lib/helper.js:112:23)
  withPage `(test/helpers/with-page.js:9:14)`

Can we just delete it?
Also, I added condition for case when content-type is set manual

[sindresorhus]

test case fails because of some strange puppeteer error

Try to do some debugging. You could start by Googling the error.

[gydroperit]

Did it

[gydroperit]

Ping

[sholladay]

LGTM