bug symfony#17790 [Config] Fix EnumNodeDefinition to allow building enum nodes with one element (ogizanagi)

This PR was merged into the 2.8 branch.

Discussion
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[Config] Fix EnumNodeDefinition to allow building enum nodes with one element

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#15433, symfony#17774
| License       | MIT
| Doc PR        | -

Commits
-------

e9111e4 [Config] Fix EnumNodeDefinition to allow building enum nodes with one element

Author: fabpot

src/Symfony/Component/Config/Definition/Builder/EnumNodeDefinition.php

@@ -31,8 +31,8 @@ public function values(array $values)
     {
         $values = array_unique($values);
 
-        if (count($values) <= 1) {
-            throw new \InvalidArgumentException('->values() must be called with at least two distinct values.');
+        if (empty($values)) {
+            throw new \InvalidArgumentException('->values() must be called with at least one value.');
         }
 
         $this->values = $values;

src/Symfony/Component/Config/Tests/Definition/Builder/EnumNodeDefinitionTest.php

@@ -15,14 +15,22 @@
 
 class EnumNodeDefinitionTest extends \PHPUnit_Framework_TestCase
 {
-    /**
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage ->values() must be called with at least two distinct values.
-     */
-    public function testNoDistinctValues()
+    public function testWithOneValue()
+    {
+        $def = new EnumNodeDefinition('foo');
+        $def->values(array('foo'));
+
+        $node = $def->getNode();
+        $this->assertEquals(array('foo'), $node->getValues());
+    }
+
+    public function testWithOneDistinctValue()
     {
         $def = new EnumNodeDefinition('foo');
         $def->values(array('foo', 'foo'));
+
+        $node = $def->getNode();
+        $this->assertEquals(array('foo'), $node->getValues());
     }
 
     /**
@@ -35,6 +43,16 @@ public function testNoValuesPassed()
         $def->getNode();
     }
 
+    /**
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage ->values() must be called with at least one value.
+     */
+    public function testWithNoValues()
+    {
+        $def = new EnumNodeDefinition('foo');
+        $def->values(array());
+    }
+
     public function testGetNode()
     {
         $def = new EnumNodeDefinition('foo');