Allow unassign user from an issue

refs #308

Author: Art4

src/Redmine/Api/Issue.php

@@ -160,9 +160,14 @@ public function update($id, array $params)
             'due_date' => null,
         ];
         $params = $this->cleanParams($params);
-        $params = $this->sanitizeParams($defaults, $params);
+        $sanitizedParams = $this->sanitizeParams($defaults, $params);
 
-        $xml = $this->buildXML($params);
+        // Allow assigned_to_id to be `` (empty string) to unassign a user from an issue
+        if (array_key_exists('assigned_to_id', $params) && $params['assigned_to_id'] === '') {
+            $sanitizedParams['assigned_to_id'] = '';
+        }
+
+        $xml = $this->buildXML($sanitizedParams);
 
         return $this->put('/issues/'.$id.'.xml', $xml->asXML());
     }

tests/Unit/Api/IssueTest.php

@@ -887,4 +887,70 @@ public function testBuildXmlWithWatcherAndUploadAndCustomFieldAndStandard()
         // Perform the tests
         $api->create($parameters);
     }
+
+    /**
+     * Test assign an user to an issue
+     *
+     * @test
+     */
+    public function testAssignUserToAnIssue()
+    {
+        // Test values
+        $parameters = [
+            'assigned_to_id' => 5,
+        ];
+
+        // Create the used mock objects
+        $client = $this->createMock(Client::class);
+        $client->expects($this->once())
+            ->method('requestPut')
+            ->with(
+                '/issues/5.xml',
+                $this->logicalAnd(
+                    $this->stringStartsWith('<?xml version="1.0"?>'."\n".'<issue>'),
+                    $this->stringContains('<assigned_to_id>5</assigned_to_id>'),
+                    $this->stringEndsWith('</issue>'."\n"),
+
+                )
+            );
+
+        // Create the object under test
+        $api = new Issue($client);
+
+        // Perform the tests
+        $api->update(5, $parameters);
+    }
+
+    /**
+     * Test unassign an user from an issue
+     *
+     * @test
+     */
+    public function testUnassignUserFromAnIssue()
+    {
+        // Test values
+        $parameters = [
+            'assigned_to_id' => "",
+        ];
+
+        // Create the used mock objects
+        $client = $this->createMock(Client::class);
+        $client->expects($this->once())
+            ->method('requestPut')
+            ->with(
+                '/issues/5.xml',
+                $this->logicalAnd(
+                    $this->stringStartsWith('<?xml version="1.0"?>'."\n".'<issue>'),
+                    $this->stringContains('<assigned_to_id></assigned_to_id>'),
+                    $this->stringEndsWith('</issue>'."\n"),
+
+                )
+            );
+
+        // Create the object under test
+        $api = new Issue($client);
+
+        // Perform the tests
+        $api->update(5, $parameters);
+    }
 }