Adds separate file for \PHPUnit_Framework_TestCase shim.

Author: Potherca

src/Shim/Compatibility/TestCase/PHPUnit_Framework_TestCase.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * The `PHPUnit_Framework_TestCase` class  was added in PHPUnit v2.0 and
+ * removed in PHPUnit v6.0, where it was replaced by the namespaced
+ * `\PHPUnit\Framework\TestCase`.
+ *
+ * In order to allow developers to migrate their code before PHPUnit v6 was
+ * released a "Forward Compatibility Layer" was added to PHPUnit v4.8 and v5.4
+ * which also contained the `PHPUnit\Framework\TestCase` class.
+ *
+ * This means that for projects that use an older version of PHPUnit, the
+ * namespaced class is not available and for newer projects the "underscored"
+ * version is missing.
+ *
+ * This file makes sure that `\PHPUnit_Framework_TestCase` always exist.
+ */
+namespace {
+    if (class_exists('\PHPUnit\Framework\TestCase') === true
+        && class_exists('\PHPUnit_Framework_TestCase') === false
+    ) {
+        abstract class PHPUnit_Framework_TestCase extends \PHPUnit\Framework\TestCase {}
+    }
+}
+
+/*EOF*/