only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/block_content/src/Tests/BlockContentValidationTest.php
@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block_content\Tests\BlockContentValidationTest.
+ */
+
+namespace Drupal\block_content\Tests;
+
+/**
+ * Tests block content validation constraints.
+ *
+ * @group block_content
+ */
+class BlockContentValidationTest extends BlockContentTestBase {
+
+  /**
+   * Tests the block content validation constraints.
+   */
+  public function testValidation() {
+    // Add a block.
+    $description = $this->randomMachineName();
+    $block = $this->createBlockContent($description, 'basic', FALSE);
+    // Validate the block.
+    $violations = $block->validate();
+    // Make sure we have no violations.
+    $this->assertEqual(count($violations), 0);
+    // Save the block.
+    $block->save();
+
+    // Add another block with the same description.
+    $block = $this->createBlockContent($description, 'basic', FALSE);
+    // Validate this block.
+    $violations = $block->validate();
+    // Make sure we have 1 violation.
+    $this->assertEqual(count($violations), 1);
+    // Make sure the violation is on the info property
+    $this->assertEqual($violations[0]->getPropertyPath(), 'info');
+    // Make sure the message is correct.
+    $this->assertEqual($violations[0]->getMessage(), format_string('A block with description %value already exists.', [
+      '%value' => $block->label(),
+    ]));
+  }
+
+}