Add PHPUnit configuration and update ignores

Author: gsteel

.gitattributes

@@ -1,2 +1,9 @@
 tests/ export-ignore
 .github/ export-ignore
+.gitignore export-ignore
+.gitattributes export-ignore
+.php-cs-fixer.php export-ignore
+CHANGELOG.md export-ignore
+composer.lock export-ignore
+phpstan.neon export-ignore
+phpunit.xml.dist export-ignore

.gitignore

@@ -1,4 +1,4 @@
 .idea/
-.phpunit.result.cache
 .php-cs-fixer.cache
 vendor/
+.phpunit.cache

phpunit.xml.dist

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+        bootstrap="./vendor/autoload.php"
+        colors="true"
+        cacheDirectory=".phpunit.cache"
+        displayDetailsOnAllIssues="true"
+        failOnWarning="true"
+        failOnNotice="true"
+        failOnDeprecation="true"
+        failOnPhpunitDeprecation="true"
+>
+    <testsuites>
+        <testsuite name="Tests">
+            <directory>./tests/</directory>
+        </testsuite>
+    </testsuites>
+    <source ignoreIndirectDeprecations="true">
+        <include>
+            <directory suffix=".php">./src</directory>
+        </include>
+    </source>
+</phpunit>