dev: php-tuf#143 Add basic PHPUnit code coverage setup (php-tuf#144)

Author: star-szr

.gitignore

@@ -1,3 +1,5 @@
+/.phpunit.result.cache
 /composer.lock
 /phpstan.neon
+/var
 /vendor

DEVELOP.md

@@ -21,6 +21,13 @@ To run a single test use PHPUnit's `--filter` option:
 ddev exec phpunit ./tests --debug --filter=testCannotProtectNonComposerRepository
 ```
 
+### Checking code coverage
+
+```
+ddev xdebug
+ddev composer coverage
+```
+
 ## Linting and fixing
 
 Linting for syntax, then style:

composer.json

@@ -44,6 +44,10 @@
         "slevomat/coding-standard": "^8.28"
     },
     "scripts": {
+        "coverage": [
+            "@putenv XDEBUG_MODE=coverage",
+            "phpunit --coverage-text --color=always --testdox"
+        ],
         "phpcs": "phpcs",
         "phpcbf": "phpcbf",
         "phpstan": "phpstan",

phpunit.xml

@@ -0,0 +1,17 @@
+<phpunit
+    bootstrap="vendor/autoload.php"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true">
+    <testsuites>
+        <testsuite name="Tests">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+    <coverage cacheDirectory="var/phpunit/coverage-cache" processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">src</directory>
+        </include>
+    </coverage>
+</phpunit>