diff --git a/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTest.php b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTest.php
index e853dd0..da6d85e 100644
--- a/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTest.php
+++ b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTest.php
@@ -39,23 +39,40 @@ class LogMessageParserTest extends UnitTestCase {
    *   An array with the expected values after the test has run.
    *    - message: The expected parsed message.
    *    - context: The expected values of the placeholders.
-   * @param bool $stringable_placeholders
-   *   A boolean flag indicating if the placeholders should be convertible
-   *   into strings.
    *
    * @dataProvider providerTestParseMessagePlaceholders
    * @covers ::parseMessagePlaceholders
    */
-  public function testParseMessagePlaceholders(array $value, array $expected, $stringable_placeholders) {
+  public function testParseMessagePlaceholders(array $value, array $expected) {
+    $parser = new LogMessageParser();
+
+    $message_placeholders = $parser->parseMessagePlaceholders($value['message'], $value['context']);
+    $this->assertEquals($expected['message'], $value['message']);
+    $this->assertEquals($expected['context'], $message_placeholders);
+  }
+
+  /**
+   * Test for LogMessageParserTrait::parseMessagePlaceholders()
+   *
+   * @param array $value
+   *   An array containing:
+   *    - message: A string that contains a message with placeholders.
+   *    - context: An array with placeholder values.
+   * @param array $expected
+   *   An array with the expected values after the test has run.
+   *    - message: The expected parsed message.
+   *    - context: The expected values of the placeholders.
+   *
+   * @dataProvider providerTestParseMessageNonStringablePlaceholders
+   * @covers ::parseMessagePlaceholders
+   */
+  public function testParseMessageInvalidPlaceholders(array $value, array $expected) {
     $parser = new LogMessageParser();
     try {
       $message_placeholders = $parser->parseMessagePlaceholders($value['message'], $value['context']);
-      $this->assertEquals($expected['message'], $value['message']);
-      $this->assertEquals($expected['context'], $message_placeholders);
-      $this->assertTrue($stringable_placeholders);
+      $this->fail("Never executed.");
     }
     catch (InvalidArgumentException $e) {
-      $this->assertFalse($stringable_placeholders);
       $this->assertStringStartsWith('Log context contains non-string value for key', $e->getMessage());
     }
   }
@@ -64,86 +81,85 @@ public function testParseMessagePlaceholders(array $value, array $expected, $str
    * Data provider for testParseMessagePlaceholders().
    */
   public function providerTestParseMessagePlaceholders() {
+    // @codingStandardsIgnoreStart
     return [
       // PSR3 only message.
       [
         ['message' => 'User {username} created', 'context' => ['username' => 'Dries']],
         ['message' => 'User @username created', 'context' => ['@username' => 'Dries']],
-        TRUE,
       ],
       // PSR3 style mixed in a format_string style message.
       [
         ['message' => 'User {username} created @time', 'context' => ['username' => 'Dries', '@time' => 'now']],
         ['message' => 'User @username created @time', 'context' => ['@username' => 'Dries', '@time' => 'now']],
-        TRUE,
       ],
       // format_string style message only.
       [
         ['message' => 'User @username created', 'context' => ['@username' => 'Dries']],
         ['message' => 'User @username created', 'context' => ['@username' => 'Dries']],
-        TRUE,
       ],
       // format_string style message only.
       [
         ['message' => 'Example :url', 'context' => [':url' => 'http://example.com']],
         ['message' => 'Example :url', 'context' => [':url' => 'http://example.com']],
-        TRUE,
       ],
       // Message without placeholders but wildcard characters.
       [
         ['message' => 'User W-\\};~{&! created @', 'context' => ['' => '']],
         ['message' => 'User W-\\};~{&! created @', 'context' => []],
-        TRUE,
       ],
       // Message with double PSR3 style messages.
       [
         ['message' => 'Test {with} two {encapsuled} strings', 'context' => ['with' => 'together', 'encapsuled' => 'awesome']],
         ['message' => 'Test @with two @encapsuled strings', 'context' => ['@with' => 'together', '@encapsuled' => 'awesome']],
-        TRUE,
       ],
-      // Placeholders not convertible into a string.
+      // Placeholders convertible into a string.
       [
-        ['message' => 'array @a', 'context' => ['@a' => []]],
-        ['message' => 'array @a', 'context' => ['@a' => []]],
-        FALSE,
+        ['message' => 'object @b', 'context' => ['@b' => new StringConvertible()]],
+        ['message' => 'object @b', 'context' => ['@b' => 'convertible']],
+      ],
+      // Message without placeholders, but with other context values.
+      [
+        ['message' => 'message', 'context' => ['not_a_placeholder' => new NotStringConvertible()]],
+        ['message' => 'message', 'context' => []], // All non placeholders are filtered out.
       ],
+    ];
+    // @codingStandardsIgnoreEnd
+  }
+
+  /**
+   * Data provider for testParseMessageInvalidPlaceholders().
+   */
+  public function providerTestParseMessageNonStringablePlaceholders() {
+    // @codingStandardsIgnoreStart
+    return [
       // Placeholders not convertible into a string.
       [
-        ['message' => 'object @b', 'context' => ['@b' => new StringConvertible()]],
-        ['message' => 'object @b', 'context' => ['@b' => 'convertible']],
-        TRUE,
+        ['message' => 'array @a', 'context' => ['@a' => []]],
+        ['message' => 'array @a', 'context' => ['@a' => []]],
       ],
       // Placeholders not convertible into a string.
       [
         ['message' => 'object @b', 'context' => ['@b' => new NotStringConvertible()]],
         ['message' => 'object @b', 'context' => ['@b' => new NotStringConvertible()]],
-        FALSE,
       ],
       // Closures are not convertible into a string.
       [
         ['message' => 'closure @c', 'context' => ['@c' => function() {} ]],
         ['message' => 'closure @c', 'context' => ['@c' => function() {} ]],
-        FALSE,
       ],
       // Resources cannot be converted into a string.
       [
         ['message' => 'resource @r', 'context' => ['@r' => fopen('php://memory', 'r+') ]],
         ['message' => 'resource @r', 'context' => ['@r' => fopen('php://memory', 'r+') ]],
-        FALSE,
       ],
       // Placeholders not converible into strings that are not the first placeholder.
       [
         ['message' => 'mixed @a @b @c', 'context' => ['@a' => 123, '@b' => [1], '@c' => TRUE]],
         ['message' => 'mixed @a @b @c', 'context' => ['@a' => 123, '@b' => [1], '@c' => TRUE]],
-        FALSE,
-      ],
-      // Message without placeholders, but with other context values.
-      [
-        ['message' => 'message', 'context' => ['not_a_placeholder' => new NotStringConvertible()]],
-        ['message' => 'message', 'context' => []],  // All non placeholders are filtered out.
-        TRUE,
       ],
     ];
+    // @codingStandardsIgnoreEnd
   }
 
 }