Nyholm / psr7

        $this->assertSame(['Bam'], $r2->getHeader('baz'));

    }

    public function testWithHeaderAsArray()

    {

        $r = new Response(200, ['Foo' => 'Bar']);

        $r2 = $r->withHeader('baZ', ['Bam', 'Bar']);

        $this->assertSame(['Foo' => ['Bar']], $r->getHeaders());

        $this->assertSame(['Foo' => ['Bar'], 'baZ' => ['Bam', 'Bar']], $r2->getHeaders());

        $this->assertSame('Bam, Bar', $r2->getHeaderLine('baz'));

        $this->assertSame(['Bam', 'Bar'], $r2->getHeader('baz'));

    }

    public function testWithHeaderReplacesDifferentCase()

    {

        $this->assertSame(['Bar', 'Baz'], $r2->getHeader('foo'));

    }

    public function testWithAddedHeaderAsArray()

    {

        $r = new Response(200, ['Foo' => 'Bar']);

        $r2 = $r->withAddedHeader('foO', ['Baz', 'Bam']);

        $this->assertSame(['Foo' => ['Bar']], $r->getHeaders());

        $this->assertSame(['Foo' => ['Bar', 'Baz', 'Bam']], $r2->getHeaders());

        $this->assertSame('Bar, Baz, Bam', $r2->getHeaderLine('foo'));

        $this->assertSame(['Bar', 'Baz', 'Bam'], $r2->getHeader('foo'));

    }

    public function testWithAddedHeaderThatDoesNotExist()

    {