diff --git a/core/modules/config/src/Tests/ConfigDiffTest.php b/core/modules/config/src/Tests/ConfigDiffTest.php
index 10f6902..12b948d 100644
--- a/core/modules/config/src/Tests/ConfigDiffTest.php
+++ b/core/modules/config/src/Tests/ConfigDiffTest.php
@@ -52,9 +52,9 @@ function testDiff() {
     // Verify that the diff reflects a change.
     $diff = \Drupal::service('config.manager')->diff($active, $staging, $config_name);
     $edits = $diff->getEdits();
-    $this->assertEqual($edits[0]->type, 'change', 'The first item in the diff is a change.');
-    $this->assertEqual($edits[0]->orig[0], $change_key . ': ' . $original_data[$change_key], format_string("The active value for key '%change_key' is '%original_data'.", array('%change_key' => $change_key, '%original_data' => $original_data[$change_key])));
-    $this->assertEqual($edits[0]->closing[0], $change_key . ': ' . $change_data, format_string("The staging value for key '%change_key' is '%change_data'.", array('%change_key' => $change_key, '%change_data' => $change_data)));
+    $this->assertYamlEdit($edits, $change_key, 'change',
+      [$change_key . ': ' . $original_data[$change_key]],
+      [$change_key . ': ' . $change_data]);
 
     // Reset data back to original, and remove a key
     $staging_data = $original_data;
@@ -64,10 +64,11 @@ function testDiff() {
     // Verify that the diff reflects a removed key.
     $diff = \Drupal::service('config.manager')->diff($active, $staging, $config_name);
     $edits = $diff->getEdits();
-    $this->assertEqual($edits[0]->type, 'copy', 'The first item in the diff is a copy.');
-    $this->assertEqual($edits[1]->type, 'delete', 'The second item in the diff is a delete.');
-    $this->assertEqual($edits[1]->orig[0], $remove_key . ': ' . $original_data[$remove_key], format_string("The active value for key '%remove_key' is '%original_data'.", array('%remove_key' => $remove_key, '%original_data' => $original_data[$remove_key])));
-    $this->assertFalse($edits[1]->closing, format_string("The key '%remove_key' does not exist in staging.", array('%remove_key' => $remove_key)));
+    $this->assertYamlEdit($edits, $change_key, 'copy');
+    $this->assertYamlEdit($edits, $remove_key, 'delete',
+      [$remove_key . ': ' . $original_data[$remove_key]],
+      FALSE
+    );
 
     // Reset data back to original and add a key
     $staging_data = $original_data;
@@ -77,10 +78,8 @@ function testDiff() {
     // Verify that the diff reflects an added key.
     $diff = \Drupal::service('config.manager')->diff($active, $staging, $config_name);
     $edits = $diff->getEdits();
-    $this->assertEqual($edits[0]->type, 'copy', 'The first item in the diff is a copy.');
-    $this->assertEqual($edits[1]->type, 'add', 'The second item in the diff is an add.');
-    $this->assertFalse($edits[1]->orig, format_string("The key '%add_key' does not exist in active.", array('%add_key' => $add_key)));
-    $this->assertEqual($edits[1]->closing[0], $add_key . ': ' . $add_data, format_string("The staging value for key '%add_key' is '%add_data'.", array('%add_key' => $add_key, '%add_data' => $add_data)));
+    $this->assertYamlEdit($edits, $change_key, 'copy');
+    $this->assertYamlEdit($edits, $add_key, 'add', FALSE, [$add_key . ': ' . $add_data]);
 
     // Test diffing a renamed config entity.
     $test_entity_id = $this->randomMachineName();
@@ -105,10 +104,11 @@ function testDiff() {
 
     $diff = \Drupal::service('config.manager')->diff($active, $staging, 'config_test.dynamic.' . $new_test_entity_id, $config_name);
     $edits = $diff->getEdits();
-    $this->assertEqual($edits[0]->type, 'copy',  'The first item in the diff is a copy.');
-    $this->assertEqual($edits[1]->type, 'change',  'The second item in the diff is a change.');
-    $this->assertEqual($edits[1]->orig, array('id: ' . $new_test_entity_id));
-    $this->assertEqual($edits[1]->closing, array('id: ' . $test_entity_id));
+    $this->assertYamlEdit($edits, 'uuid', 'copy');
+    $this->assertYamlEdit($edits, 'id', 'change',
+      ['id: ' . $new_test_entity_id],
+      ['id: ' . $test_entity_id]);
+    $this->assertYamlEdit($edits, 'label', 'copy');
     $this->assertEqual($edits[2]->type, 'copy',  'The third item in the diff is a copy.');
     $this->assertEqual(count($edits), 3, 'There are three items in the diff.');
   }
@@ -141,10 +141,54 @@ function testCollectionDiff() {
     // Test that the differences are detected when diffing the collection.
     $diff = \Drupal::service('config.manager')->diff($active, $staging, $config_name, NULL, 'test');
     $edits = $diff->getEdits();
-    $this->assertEqual($edits[0]->type, 'change',  'The second item in the diff is a copy.');
-    $this->assertEqual($edits[0]->orig, array('foo: bar'));
-    $this->assertEqual($edits[0]->closing, array('foo: baz'));
-    $this->assertEqual($edits[1]->type, 'copy',  'The second item in the diff is a copy.');
+    $this->assertYamlEdit($edits, 'foo', 'change', ['foo: bar'], ['foo: baz']);
+  }
+
+  /**
+   * Helper method to test that an edit is found in a diff'd yaml file.
+   *
+   * @param array $edits
+   *   A list of edits.
+   * @param $field
+   *   The field key that is being asserted.
+   * @param $type
+   *   The type of edit that is being asserted.
+   * @param mixed $orig
+   *   (optional) The original value of of the edit. If not supplied, assertion is skipped.
+   * @param mixed $closing
+   *   (optional) The closing value of of the edit. If not supplied, assertion is skipped.
+   */
+  protected function assertYamlEdit(array $edits, $field, $type, $orig = null, $closing = null) {
+    $match = FALSE;
+    foreach ($edits as $edit) {
+      // Choose which section to search for the field.
+      $haystack = $type == 'add' ? $edit->closing : $edit->orig;
+      // Look through each line and try and find the key.
+      if (is_array($haystack)) {
+        foreach ($haystack as $item) {
+          if (strpos($item, $field . ':') === 0) {
+            $match = TRUE;
+            // Assert that the edit is of the type specified.
+            $this->assertEqual($edit->type, $type, "The $field item in the diff is a $type");
+            // If an original value was given, assert that it matches.
+            if (isset($orig)) {
+              $this->assertIdentical($edit->orig, $orig, "The original value for key '$field' is correct.");
+            }
+            // If a closing value was given, assert that it matches.
+            if (isset($closing)) {
+              $this->assertIdentical($edit->closing, $closing, "The closing value for key '$field' is correct.");
+            }
+            // Break out of the search entirely.
+            break 2;
+          }
+        }
+      }
+    }
+
+    // If we didn't match anything, fail.
+    if (!$match) {
+      $this->fail("$field edit was not matched");
+    }
   }
 
 }
diff --git a/core/modules/config/src/Tests/ConfigSingleImportExportTest.php b/core/modules/config/src/Tests/ConfigSingleImportExportTest.php
index 7b3336d..922f113 100644
--- a/core/modules/config/src/Tests/ConfigSingleImportExportTest.php
+++ b/core/modules/config/src/Tests/ConfigSingleImportExportTest.php
@@ -179,8 +179,8 @@ public function testExport() {
     $this->assertFieldByXPath('//select[@name="config_name"]//option[@selected="selected"]', t('Fallback date format'), 'The fallback date format config entity is selected when specified in the URL.');
 
     $fallback_date = \Drupal::entityManager()->getStorage('date_format')->load('fallback');
-    $data = Yaml::encode($fallback_date->toArray());
-    $this->assertFieldByXPath('//textarea[@name="export"]', $data, 'The fallback date format config entity export code is displayed.');
+    $yaml_text = (string) $this->xpath('//textarea[@name="export"]')[0];
+    $this->assertEqual(Yaml::decode($yaml_text), $fallback_date->toArray(), 'The fallback date format config entity export code is displayed.');
   }
 
 }
diff --git a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
index 184e07b..8c7d123 100644
--- a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
+++ b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
@@ -47,15 +47,15 @@ public function testStandardConfig() {
     $skipped_config = [];
     // \Drupal\simpletest\WebTestBase::installParameters() uses
     // simpletest@example.com as mail address.
-    $skipped_config['contact.form.feedback'][] = ' - simpletest@example.com';
+    $skipped_config['contact.form.feedback'][] = '- simpletest@example.com';
     // \Drupal\filter\Entity\FilterFormat::toArray() drops the roles of filter
     // formats.
     $skipped_config['filter.format.basic_html'][] = 'roles:';
-    $skipped_config['filter.format.basic_html'][] = ' - authenticated';
+    $skipped_config['filter.format.basic_html'][] = '- authenticated';
     $skipped_config['filter.format.full_html'][] = 'roles:';
-    $skipped_config['filter.format.full_html'][] = ' - administrator';
+    $skipped_config['filter.format.full_html'][] = '- administrator';
     $skipped_config['filter.format.restricted_html'][] = 'roles:';
-    $skipped_config['filter.format.restricted_html'][] = ' - anonymous';
+    $skipped_config['filter.format.restricted_html'][] = '- anonymous';
 
     $this->assertInstalledConfig($skipped_config);
   }