Tests: add dedicated test for the SyntaxError::getLine() method

src/Errors/SyntaxError.php

@@ -16,7 +16,7 @@ public function getLine()
     {
         preg_match('~on line ([0-9]+)$~', $this->message, $matches);
 
-        if ($matches && isset($matches[1])) {
+        if (isset($matches[1])) {
             return (int) $matches[1];
         }
 

tests/Unit/Errors/SyntaxErrorGetLineTest.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace PHP_Parallel_Lint\PhpParallelLint\Tests\Unit\Errors;
+
+use PHP_Parallel_Lint\PhpParallelLint\Errors\SyntaxError;
+use PHP_Parallel_Lint\PhpParallelLint\Tests\UnitTestCase;
+
+/**
+ * @covers \PHP_Parallel_Lint\PhpParallelLint\Errors\SyntaxError::getLine
+ */
+class SyntaxErrorGetLineTest extends UnitTestCase
+{
+    /**
+     * Test retrieving the line on which the error occured.
+     *
+     * @dataProvider dataGetLine
+     *
+     * @param string $message  The message input to run the test with.
+     * @param string $expected The expected method return value.
+     *
+     * @return void
+     */
+    public function testGetLine($message, $expected)
+    {
+        $error = new SyntaxError('test.php', $message);
+        $this->assertSame($expected, $error->getLine());
+    }
+
+    /**
+     * Data provider.
+     *
+     * @return array
+     */
+    public function dataGetLine()
+    {
+        return array(
+            'Message: empty string' => array(
+                'message'  => '',
+                'expected' => null,
+            ),
+            'Message: plain text, no line number' => array(
+                'message'  => 'plain text',
+                'expected' => null,
+            ),
+            'Message: error with line number at end' => array(
+                'message'  => 'Parse error: syntax error, unexpected token "<", expecting end of file in Source string on line 10',
+                'expected' => 10,
+            ),
+            'Message: error with line number at end with trailing whitespace' => array(
+                'message'  => 'Parse error: syntax error, unexpected token "<", expecting end of file in Source string on line 10   ',
+                'expected' => 10,
+            ),
+            'Message: error with line number at end and in the message text [1]' => array(
+                'message'  => 'Parse error: Unclosed \'{\' on line 2 in test.php on line 5',
+                'expected' => 5,
+            ),
+            'Message: error with line number at end and in the message text [2]' => array(
+                'message'  => 'Parse error: Unterminated comment starting on line 2 in test.php on line 3',
+                'expected' => 3,
+            ),
+            'Message: error with line number at end, large number' => array(
+                'message'  => 'The (real) cast has been removed, use (float) instead in test.php on line 3534384',
+                'expected' => 3534384,
+            ),
+        );
+    }
+}