Test coverage and docs for multiple instances of same URL arg

Author: agh1

USAGE.md

@@ -50,6 +50,23 @@ echo $response->body();
 echo $response->headers();
 ```
 
+#### GET with array of values
+
+```
+$query_params = [
+    'aggregated_by' => 'month',
+    'subusers' => ['one', 'two', 'three'],
+    'start_date' => '2019-01-01',
+    'end_date' => '2019-01-31',
+];
+$request_headers = ['X-Mock: 200'];
+$retryOnLimit = true;
+$response = $client->subusers()->stats()->get(null, $query_params, $request_headers, $retryOnLimit);
+echo $response->statusCode();
+echo $response->body();
+echo $response->headers();
+```
+
 <a name="delete"></a>
 ## DELETE
 

lib/Client.php

@@ -324,13 +324,15 @@ public function setIsConcurrentRequest($isConcurrent)
      * Build the final URL to be passed
      *
      * @param array $queryParams an array of all the query parameters
+     *   Nested arrays will resolve to multiple instances of the same parameter
      *
      * @return string
      */
     private function buildUrl($queryParams = null)
     {
         $path = '/' . implode('/', $this->path);
         if (isset($queryParams)) {
+            // Regex replaces `[0]=`, `[1]=`, etc. with `=`.
             $path .= '?' . preg_replace('/%5B(?:\d|[1-9]\d+)%5D=/', '=', http_build_query($queryParams));
         }
         return sprintf('%s%s%s', $this->host, $this->version ?: '', $path);

test/unit/ClientTest.php

@@ -204,6 +204,22 @@ public function testThrowExceptionOnInvalidCall()
         $client->get();
     }
 
+    public function testFormRepeatUrlArgs()
+    {
+        $client = new Client('https://localhost:4010');
+
+        $testParams = [
+          'thing' => 'stuff',
+          'foo' => [
+            'bar',
+            'bat',
+            'baz',
+          ],
+        ];
+        $result = $this->callMethod($client, 'buildUrl', [$testParams]);
+        $this->assertEquals($result, 'https://localhost:4010/?thing=stuff&foo=bar&foo=bat&foo=baz');
+    }
+
     /**
      * @param object $obj
      * @param string $name