[7.x] Add ArrayAccess support for Http client get requests

[dmason30]

Fixes #32398.

TL;DR
Fixes an Undefined index: Content-Type exception and allows access to get request params via array access $request['foo'] and in turn allows you to make assertions such as $request['foo'] === 'bar'.

Description:

I was writing a test similar to the below and when running it was greeted with an ErrorException of Undefined index: Content-Type.

public function testGet()
{
    \Http::fake(['*' => \Http::response(['response' =>'Test return data'], 200)]);

    \Http::acceptJson()
        ->get('https://google.com', ['apikey' => 'aaa-bbb-ccc'])
        ->json()

    \Http::assertSent(function (Request $request) {
        $this->assertStringStartsWith('https://google.com', $request->url());
        $this->assertSame('aaa-bbb-ccc', $request['apikey']); // Undefined index: Content-Type
        return true;
    });
}

Cause

Looking at the line causing the error it seems it just needs to check if the key it is searching for exists in the headers array before trying to access it:

Illuminate/Http/Client/Request.php:

public function isForm()
{
    return $this->hasHeader('Content-Type', 'application/x-www-form-urlencoded');
}

public function hasHeader($key, $value = null)
{
    ...
    // Added an Arr::has($headers, $key) here. This ⬇️ was causing the error. 
    return empty(array_diff($value, $this->headers()[$key]));
}

Initial fix & New error found

So I initially set out to fix hasHeader so that it checks the $key exists in the array returned by $this->headers() and I ran the tests and got the same error Undefined index: Content-Type but from a different location:

Illuminate/Http/Client/Request.php:

public function isJson()
{
    return Str::contains($this->header('Content-Type')[0], 'json');
}

public function header($key)
{
    // Caused by this line ⬇️ 
    return $this->headers()[$key];
}

Adding ArrayAccess Support

I then added Arr::get check in the header($key) method and then discovered that there is not any existing support for accessing get query parameters via $request and was met with another Undefined index: foo in the below test:

public function testGetWithArrayQueryParam()
{
    $this->factory->fake();

    $this->factory->get('http://foo.com/get', ['foo' => 'bar']);

    $this->factory->assertSent(function (Request $request) {
        return $request->url() === 'http://foo.com/get?foo=bar'
            && $request['foo'] === 'bar'; // Undefined index: foo
    });
}

So this change gets the query parameters either from $options['query'] or by extracting them from the $url. It handles the below with the tests adjusted to prove it.

Http::get('http://foo.com');
Http::get('http://foo.com?foo=bar');
Http::get('http://foo.com', ['foo' => 'bar']);
Http::get('http://foo.com', 'foo=bar');
Http::get('http://foo.com/get?foo=bar&page=1', ['hello' => 'world']); // Hello world overwrites params
Http::get('http://foo.com', ['foo;bar; space test' => 'laravel']);

Then you can do assertions on the $request data:

Http::assertSent(function (Request $request) {
    return $request->url() === 'http://foo.com/get?foo=bar'
        && $request['foo'] === 'bar';
});

[driesvints]

@dmason30 probably best to explain why this is needed, not just link to an issue.

[dmason30]

@driesvints Thanks done as requested.