Adjusted down to PHPUnit 8 for PHP 7.2

.github/workflows/tests.yml

@@ -16,7 +16,7 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: '7.2'
-          tools: phpunit:9,psalm
+          tools: phpunit:8,psalm
 
       - name: Setup problem matchers for PHPUnit
         run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"

README.md

@@ -41,7 +41,7 @@ API requests need to be authenticated as admin for performance data to be sent.
 
 ## Tests
 
-Tests require [Brain Monkey](https://github.com/Brain-WP/BrainMonkey) (included in dependencies) and PHPUnit 9 (not included).
+Tests require [Brain Monkey](https://github.com/Brain-WP/BrainMonkey) (included in dependencies) and PHPUnit 8 (not included).
 
 ```bash
 phpunit

phpunit.xml

@@ -1,16 +1,15 @@
-<?xml version="1.0"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="vendor/autoload.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
-  <coverage processUncoveredFiles="true">
-    <include>
-      <directory suffix=".php">src</directory>
-    </include>
-    <exclude>
-      <directory suffix=".php">src/mustache/cache</directory>
-    </exclude>
-  </coverage>
-  <testsuites>
-    <testsuite name="Laps">
-      <directory>tests</directory>
-    </testsuite>
-  </testsuites>
+<phpunit bootstrap="vendor/autoload.php">
+    <testsuites>
+        <testsuite name="Laps">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">src</directory>
+            <exclude>
+                <directory suffix=".php">src/mustache/cache</directory>
+            </exclude>
+        </whitelist>
+    </filter>
 </phpunit>