Correct issue with Google refreshToken() method

src/Two/GoogleProvider.php

@@ -59,6 +59,21 @@ protected function getUserByToken($token)
         return json_decode($response->getBody(), true);
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function refreshToken($refreshToken)
+    {
+        $response = $this->getRefreshTokenResponse($refreshToken);
+
+        return new Token(
+            Arr::get($response, 'access_token'),
+            Arr::get($response, 'refresh_token', $refreshToken),
+            Arr::get($response, 'expires_in'),
+            explode($this->scopeSeparator, Arr::get($response, 'scope', ''))
+        );
+    }
+
     /**
      * {@inheritdoc}
      */

tests/Fixtures/GoogleTestProviderStub.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Laravel\Socialite\Tests\Fixtures;
+
+use Laravel\Socialite\Two\GoogleProvider;
+use Laravel\Socialite\Two\User;
+use Mockery as m;
+use stdClass;
+
+class GoogleTestProviderStub extends GoogleProvider
+{
+    /**
+     * @var \GuzzleHttp\Client|\Mockery\MockInterface
+     */
+    public $http;
+
+    protected function getAuthUrl($state)
+    {
+        return $this->buildAuthUrlFromBase('http://auth.url', $state);
+    }
+
+    protected function getTokenUrl()
+    {
+        return 'http://token.url';
+    }
+
+    protected function getUserByToken($token)
+    {
+        return ['id' => 'foo'];
+    }
+
+    protected function mapUserToObject(array $user)
+    {
+        return (new User)->map(['id' => $user['id']]);
+    }
+
+    /**
+     * Get a fresh instance of the Guzzle HTTP client.
+     *
+     * @return \GuzzleHttp\Client|\Mockery\MockInterface
+     */
+    protected function getHttpClient()
+    {
+        if ($this->http) {
+            return $this->http;
+        }
+
+        return $this->http = m::mock(stdClass::class);
+    }
+}

tests/OAuthTwoTest.php

@@ -7,6 +7,7 @@
 use Illuminate\Http\Request;
 use Illuminate\Support\Str;
 use Laravel\Socialite\Tests\Fixtures\FacebookTestProviderStub;
+use Laravel\Socialite\Tests\Fixtures\GoogleTestProviderStub;
 use Laravel\Socialite\Tests\Fixtures\OAuthTwoTestProviderStub;
 use Laravel\Socialite\Tests\Fixtures\OAuthTwoWithPKCETestProviderStub;
 use Laravel\Socialite\Two\InvalidStateException;
@@ -197,4 +198,23 @@ public function testUserRefreshesToken()
         $this->assertSame(3600, $token->expiresIn);
         $this->assertSame(['scope1', 'scope2'], $token->approvedScopes);
     }
+
+    public function testUserRefreshesGoogleToken()
+    {
+        $request = Request::create('/');
+        $provider = new GoogleTestProviderStub($request, 'client_id', 'client_secret', 'redirect_uri');
+        $provider->http = m::mock(stdClass::class);
+        $provider->http->expects('post')->with('http://token.url', [
+            'headers' => ['Accept' => 'application/json'],
+            'form_params' => ['grant_type' => 'refresh_token', 'client_id' => 'client_id', 'client_secret' => 'client_secret', 'refresh_token' => 'refresh_token'],
+        ])->andReturns($response = m::mock(stdClass::class));
+        $response->expects('getBody')->andReturns('{ "access_token" : "access_token", "expires_in" : 3600, "scope" : "scope1 scope2" }');
+        $token = $provider->refreshToken('refresh_token');
+
+        $this->assertInstanceOf(Token::class, $token);
+        $this->assertSame('access_token', $token->token);
+        $this->assertSame('refresh_token', $token->refreshToken);
+        $this->assertSame(3600, $token->expiresIn);
+        $this->assertSame(['scope1', 'scope2'], $token->approvedScopes);
+    }
 }