Template: close the output buffer when a template throws (→ 3.3.1)

src/Neuron/Core/Template.php

@@ -311,7 +311,14 @@ public function parse ($template = null, $text = null)
 			}
 		}
 
-		include $ctlbtmpltfiles[0];
+		try {
+			include $ctlbtmpltfiles[0];
+		} catch (\Throwable $ctlbtmplterror) {
+			// Close our buffer before rethrowing, or it stays open and
+			// swallows everything the caller outputs afterwards.
+			ob_end_clean ();
+			throw $ctlbtmplterror;
+		}
 
 		$val = ob_get_contents();
 
@@ -384,10 +391,15 @@ private function combine ($template, $parameters = [])
 			${$k} = $v;
 		}
 
-		if ($ctlbtmpltfiles = $this->getFilenames($template, true)) {
-			foreach ($ctlbtmpltfiles as $ctlbtmpltfile) {
-				include $ctlbtmpltfile;
+		try {
+			if ($ctlbtmpltfiles = $this->getFilenames($template, true)) {
+				foreach ($ctlbtmpltfiles as $ctlbtmpltfile) {
+					include $ctlbtmpltfile;
+				}
 			}
+		} catch (\Throwable $ctlbtmplterror) {
+			ob_end_clean();
+			throw $ctlbtmplterror;
 		}
 
 		$val = ob_get_contents();
@@ -418,10 +430,15 @@ private function template ($template, $parameters = [])
 			${$k} = $v;
 		}
 
-		if ($ctlbtmpltfiles = $this->getFilenames($template)) {
-			foreach ($ctlbtmpltfiles as $ctlbtmpltfile) {
-				include $ctlbtmpltfile;
+		try {
+			if ($ctlbtmpltfiles = $this->getFilenames($template)) {
+				foreach ($ctlbtmpltfiles as $ctlbtmpltfile) {
+					include $ctlbtmpltfile;
+				}
 			}
+		} catch (\Throwable $ctlbtmplterror) {
+			ob_end_clean();
+			throw $ctlbtmplterror;
 		}
 
 		$val = ob_get_contents();

tests/TemplateOutputBufferTest.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Neuron\Tests;
+
+use Neuron\Core\Template;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * A template that throws must not leave its output buffer open: the leaked
+ * buffer would swallow everything the caller prints afterwards (and makes
+ * PHPUnit re-print its whole output as the failing test's output).
+ */
+class TemplateOutputBufferTest extends TestCase
+{
+	protected function setUp (): void
+	{
+		Template::setPath (__DIR__ . '/templates/');
+	}
+
+	public static function throwingTemplates ()
+	{
+		return [
+			'parse' => [ 'buffer/throws.phpt' ],
+			'template() inside a template' => [ 'buffer/viaTemplate.phpt' ],
+			'combine() inside a template' => [ 'buffer/viaCombine.phpt' ],
+		];
+	}
+
+	/**
+	 * @dataProvider throwingTemplates
+	 */
+	public function testThrowingTemplateClosesItsBuffers ($name)
+	{
+		$level = ob_get_level ();
+
+		try {
+			(new Template ($name))->parse ();
+			$this->fail ('Expected the template exception to propagate');
+		} catch (\RuntimeException $e) {
+			$this->assertSame ('template failed', $e->getMessage ());
+		}
+
+		$this->assertSame ($level, ob_get_level ());
+	}
+
+	public function testRenderingStillReturnsTheOutput ()
+	{
+		$level = ob_get_level ();
+
+		$template = new Template ('buffer/fine.phpt');
+		$template->set ('name', 'world');
+
+		$this->assertSame ('hello world', trim ($template->parse ()));
+		$this->assertSame ($level, ob_get_level ());
+	}
+}

tests/templates/buffer/fine.phpt

@@ -0,0 +1 @@
+hello <?php echo $name; ?>

tests/templates/buffer/throws.phpt

@@ -0,0 +1 @@
+partial output<?php throw new \RuntimeException('template failed'); ?>

tests/templates/buffer/viaCombine.phpt

@@ -0,0 +1 @@
+outer<?php echo $this->combine('buffer/throws.phpt'); ?>

tests/templates/buffer/viaTemplate.phpt

@@ -0,0 +1 @@
+outer<?php echo $this->template('buffer/throws.phpt'); ?>