MDL-87905 Behat: pause incorrectly thinks terminal not interactive

When run from behat/cli/run.php, the pause command may fail because
it thinks the terminal is not interactive, even if the input and
output is passed through from an interactive terminal run.

public/admin/tool/behat/cli/run.php

@@ -224,6 +224,11 @@ if (empty($parallelrun)) {
     $cmds['singlerun'] = $runtestscommand;
 
     echo "Running single behat site:" . PHP_EOL;
+    // The inner PHP process is not marked as having an interactive terminal even if it's passed
+    // through from this one which does, so we need to pass it through as an environment variable.
+    if (function_exists('posix_isatty') && posix_isatty(STDOUT)) {
+        putenv('MOODLE_BEHAT_RUNNING_IN_TTY=1');
+    }
     passthru("php $runtestscommand", $status);
     $exitcodes['singlerun'] = $status;
     chdir($cwd);

public/lib/behat/classes/util.php

@@ -486,7 +486,7 @@ class behat_util extends testing_util {
         $posixexists = function_exists('posix_isatty');
 
         // Make sure this step is only used with interactive terminal (if detected).
-        if ($posixexists && !@posix_isatty(STDOUT)) {
+        if ($posixexists && !@posix_isatty(STDOUT) && getenv('MOODLE_BEHAT_RUNNING_IN_TTY') !== '1') {
             throw new ExpectationException('Break point should only be used with interactive terminal.', $session);
         }