Requirements checker now logs to stderr

UPGRADE.md

@@ -1,3 +1,9 @@
+
+# From 3.16.0 to 3.17.0
+
+- The requirements checker now logs its output to `stderr` instead of `stdout` per default. Set `BOX_REQUIREMENTS_CHECKER_LOG_TO_STDOUT=1` to restore the old behaviour.
+
+
 # From 3.1.3 to 3.2.0
 
 - Changes to the `Php` compactor:

doc/requirement-checker.md

@@ -135,6 +135,16 @@ $ BOX_REQUIREMENT_CHECKER=0 php box.phar
 ```
 
 
+## Logging to stdout
+
+Since version 3.17.0, box logs the requirements checker output to `stderr` per default (see: [#678](https://github.com/box-project/box/issues/678)).
+The requirements checker can be configured to output to `stdout` instead by setting `BOX_REQUIREMENTS_CHECKER_LOG_TO_STDOUT=1`:
+
+```
+$ BOX_REQUIREMENTS_CHECKER_LOG_TO_STDOUT=1 php box.phar
+```
+
+
 <br />
 <hr />
 

requirement-checker/phpunit.xml.dist

@@ -7,6 +7,9 @@
     <php>
         <!-- The width is matching the Travis one to avoid any issues with the CI -->
         <env name="COLUMNS" value="80" />
+
+        <!-- required for output buffering -->
+        <env name="BOX_REQUIREMENTS_CHECKER_LOG_TO_STDOUT" value="1" />
     </php>
 
     <testsuites>

requirement-checker/src/Printer.php

@@ -148,6 +148,11 @@ public function printv(string $message, int $verbosity, ?string $style = null):
             $this->supportColors ? $this->styles['reset'] : ''
         );
 
-        echo $message;
+        if (getenv('BOX_REQUIREMENTS_CHECKER_LOG_TO_STDOUT') === '1') {
+            // use echo/print to support output buffering
+            echo $message;
+        } else {
+            fwrite(STDERR, $message);
+        }
     }
 }