public function test_exchange_rate()
    {
        $cryptoExternalApi = $this->createMock(CryptoExternalApi::class);
        $map = [
            [Asset::BTC, Asset::BTC, Asset::ETH],
            ['1', '1', '2']
        ];
        $cryptoExternalApi->method('getExchangeRate')
            ->willReturn(1);

//            ->will($this->returnValueMap($map));


        $user = factory(User::class)->create();

        $asset = Asset::firstOrCreate(
            [
                'storage' => 'testStorage',
                'currency' => Asset::BTC,
                'value' => 1,
                'user_id' => $user->id
            ]
        );

        $asset->save();

        $asset2 = Asset::firstOrCreate(
            [
                'storage' => 'testStorage',
                'currency' => Asset::BTC,
                'value' => 2,
                'user_id' => $user->id
            ]
        );

        $asset2->save();

        $asset3 = Asset::firstOrCreate(
            [
                'storage' => 'testStorage',
                'currency' => Asset::ETH,
                'value' => 3,
                'user_id' => $user->id
            ]
        );

        $asset3->save();

        $response = $this->actingAs($user)->json('GET', route('asset.exchangeRate', $user->id));
        $response
            ->assertStatus(204);
    }