Add compatibility for PHP8

DEVELOP.rst

@@ -81,15 +81,15 @@ Installation
 
 Install prerequisites::
 
-    # Install different PHP releases.
-    brew install php@7.3 php@7.4 php@8.0 composer
+    # Install different PHP releases and Composer.
+    brew install php@7.3 php@7.4 php@8.0 brew-php-switcher composer
 
     # Select PHP version.
     brew-php-switcher 7.3
     brew-php-switcher 7.4
     brew-php-switcher 8.0
 
-    # Install xdebug extension for tracking code coverage.
+    # Install `xdebug` extension into each environment for tracking code coverage.
     pecl install xdebug
 
 Get the sources::
@@ -113,9 +113,19 @@ Running the Tests
         --mount type=bind,source=$PWD/test/provisioning/truststore,target=/vagrant/test/provisioning/truststore \
         --publish 4200:4200 --publish 5432:5432 crate/crate:nightly
 
-    # Run test suite
+    # Run test suite on current/default version of PHP
     composer run test
 
+    # Run tests on both PHP7 and PHP8 to get the full picture of coverage
+    composer run multicover
+    open build/multicover/html/index.html
+
+
+Invoke code style checks
+========================
+
+::
+
     # Run code style checks
     composer run check-style
 

composer.json

@@ -35,6 +35,8 @@
     },
     "scripts": {
         "test": "XDEBUG_MODE=coverage phpunit --coverage-clover build/logs/clover.xml",
+        "coverage-html": "XDEBUG_MODE=coverage phpunit --coverage-html build/logs/html",
+        "multicover": "./devtools/php-multicover.sh",
         "check-style": "phpcs",
         "fix-style": "phpcbf"
     }

devtools/php-multicover.sh

@@ -0,0 +1,63 @@
+#!/bin/sh
+#
+# About
+# =====
+#
+# Run tests with coverage on both PHP7 and PHP8,
+# merge coverage reports and render them as HTML.
+#
+# Please adjust the paths to the PHP interpreters
+# to fit your needs. Make sure to `pecl install xdebug`
+# in both PHP7 and PHP8 environments beforehand.
+#
+# Setup
+# =====
+#
+# Install different PHP releases and Composer::
+#
+#   brew install php@7.3 php@7.4 php@8.0 brew-php-switcher composer
+#
+# Select PHP version::
+#
+#   brew-php-switcher 7.3
+#   brew-php-switcher 7.4
+#   brew-php-switcher 8.0
+#
+# Install `xdebug` extension into each environment for tracking code coverage::
+#
+#   pecl install xdebug
+#
+# Install `phpunit-merger`::
+#
+#   composer require --dev nimut/phpunit-merger
+#
+# Please make sure to remove it before committing as it is currently not available for PHP8::
+#
+#   composer remove --dev nimut/phpunit-merger
+#
+
+# Define shortcuts to executables.
+php7=/usr/local/Cellar/php@7.4/7.4.15/bin/php
+php8=/usr/local/Cellar/php/8.0.2/bin/php
+phpunit="$(pwd)/vendor/bin/phpunit"
+phpunit_merger="$(pwd)/vendor/bin/phpunit-merger"
+
+# Prepare output directories.
+mkdir -p build/multicover/reports build/multicover/html
+rm -rf build/multicover/reports/* build/multicover/html/*
+
+# Enable coverage tracing.
+export XDEBUG_MODE=coverage
+
+# Run tests with PHP coverage output on both PHP7 and PHP8.
+echo Running tests with coverage on PHP7
+$php7 $phpunit --coverage-php build/multicover/reports/clover-php7.php
+echo; echo
+
+echo Running tests with coverage on PHP8
+$php8 $phpunit --coverage-php build/multicover/reports/clover-php8.php
+echo; echo
+
+# Merge coverage reports and generate HTML output.
+echo Merging test reports
+$php7 $phpunit_merger coverage build/multicover/reports --html=build/multicover/html /dev/null