Fixin bug with using attributes.add() on a non-live component

Author: weaverryan

src/TwigComponent/src/ComponentAttributes.php

@@ -108,10 +108,10 @@ public function add(AbstractStimulusDto $stimulusDto): self
         $controllersAttributes = $stimulusDto->toArray();
         $attributes = $this->attributes;
 
-        $attributes['data-controller'] = implode(' ', array_merge(
-            explode(' ', $attributes['data-controller']),
+        $attributes['data-controller'] = trim(implode(' ', array_merge(
+            explode(' ', $attributes['data-controller'] ?? ''),
             explode(' ', $controllersAttributes['data-controller'] ?? [])
-        ));
+        )));
         unset($controllersAttributes['data-controller']);
 
         $clone = new self($attributes);

src/TwigComponent/tests/Unit/ComponentAttributesTest.php

@@ -88,6 +88,29 @@ public function testCanAddStimulusController(): void
         ], $attributes->all());
     }
 
+    public function testCanAddStimulusControllerIfNoneAlreadyPresent(): void
+    {
+        $attributes = new ComponentAttributes([
+            'class' => 'foo',
+        ]);
+
+        $controllerDto = $this->createMock(AbstractStimulusDto::class);
+        $controllerDto->expects(self::once())
+            ->method('toArray')
+            ->willReturn([
+                'data-controller' => 'foo bar',
+                'data-foo-name-value' => 'ryan',
+            ]);
+
+        $attributes = $attributes->add($controllerDto);
+
+        $this->assertEquals([
+            'class' => 'foo',
+            'data-controller' => 'foo bar',
+            'data-foo-name-value' => 'ryan',
+        ], $attributes->all());
+    }
+
     public function testBooleanBehaviour(): void
     {
         $attributes = new ComponentAttributes(['disabled' => true]);