feat: add AbstractCommand::callSilently()

system/CLI/AbstractCommand.php

@@ -504,6 +504,31 @@ protected function call(string $command, array $arguments = [], array $options =
         return $this->commands->runCommand($command, $arguments, $this->resolveChildInteractiveState($options, $noInteractionOverride));
     }
 
+    /**
+     * Like `call()`, but suppresses the sub-command's output. Defaults to non-interactive
+     * since a silenced sub-command cannot meaningfully prompt.
+     *
+     * @param list<string>                            $arguments             Parsed arguments from command line.
+     * @param array<string, list<string>|string|null> $options               Parsed options from command line.
+     * @param bool|null                               $noInteractionOverride See `call()` for the semantics.
+     */
+    protected function callSilently(string $command, array $arguments = [], array $options = [], ?bool $noInteractionOverride = true): int
+    {
+        $priorIo = CLI::getInputOutput();
+
+        CLI::setInputOutput(new NullInputOutput());
+
+        try {
+            return $this->call($command, $arguments, $options, $noInteractionOverride);
+        } finally {
+            if ($priorIo instanceof InputOutput) {
+                CLI::setInputOutput($priorIo);
+            } else {
+                CLI::resetInputOutput();
+            }
+        }
+    }
+
     /**
      * Gets the unbound arguments that can be passed to other commands when called via the `call()` method.
      *

system/CLI/CLI.php

@@ -1166,8 +1166,14 @@ public static function resetLastWrite(): void
     }
 
     /**
-     * Testing purpose only
-     *
+     * @internal
+     */
+    public static function getInputOutput(): ?InputOutput
+    {
+        return static::$io;
+    }
+
+    /**
      * @internal
      */
     public static function setInputOutput(InputOutput $io): void
@@ -1176,8 +1182,6 @@ public static function setInputOutput(InputOutput $io): void
     }
 
     /**
-     * Testing purpose only
-     *
      * @internal
      */
     public static function resetInputOutput(): void

system/CLI/NullInputOutput.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\CLI;
+
+/**
+ * An InputOutput sink that discards all output and never reads input.
+ *
+ * Backs `AbstractCommand::callSilently()` to silence a sub-command's
+ * output when the parent wants to emit its own consolidated message instead.
+ */
+final class NullInputOutput extends InputOutput
+{
+    public function fwrite($handle, string $string): void
+    {
+    }
+
+    public function input(?string $prefix = null): string
+    {
+        return '';
+    }
+}

tests/_support/Commands/Modern/AppAboutCommand.php

@@ -62,6 +62,11 @@ public function helpMe(): int
         return $this->call('help');
     }
 
+    public function helpMeSilently(): int
+    {
+        return $this->callSilently('help');
+    }
+
     /**
      * @param array<string, list<string|null>|string|null>|null $options
      */

tests/system/CLI/AbstractCommandTest.php

@@ -34,6 +34,7 @@
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Group;
 use ReflectionClass;
+use ReflectionProperty;
 use Tests\Support\Commands\Modern\AppAboutCommand;
 use Tests\Support\Commands\Modern\InteractFixtureCommand;
 use Tests\Support\Commands\Modern\InteractiveStateProbeCommand;
@@ -257,6 +258,38 @@ public function testCommandCanCallAnotherCommand(): void
         $this->assertStringContainsString('help [options] [--] [<command_name>]', $this->getStreamFilterBuffer());
     }
 
+    public function testCallSilentlySuppressesSubCommandOutputAndReturnsExitCode(): void
+    {
+        $command = new AppAboutCommand(new Commands());
+
+        $this->assertSame(EXIT_SUCCESS, $command->helpMeSilently());
+        $this->assertSame('', $this->getStreamFilterBuffer());
+    }
+
+    public function testCallSilentlyRestoresPriorIo(): void
+    {
+        $custom = new InputOutput();
+        CLI::setInputOutput($custom);
+
+        $command = new AppAboutCommand(new Commands());
+        $command->helpMeSilently();
+
+        $this->assertSame($custom, CLI::getInputOutput());
+    }
+
+    public function testCallSilentlyResetsToFreshInputOutputWhenPriorWasNull(): void
+    {
+        $property = new ReflectionProperty(CLI::class, 'io');
+        $property->setValue(null, null);
+
+        $command = new AppAboutCommand(new Commands());
+        $command->helpMeSilently();
+
+        $current = CLI::getInputOutput();
+        $this->assertInstanceOf(InputOutput::class, $current);
+        $this->assertNotInstanceOf(NullInputOutput::class, $current);
+    }
+
     public function testRunCommand(): void
     {
         command('app:about a');

tests/system/CLI/NullInputOutputTest.php

@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\CLI;
+
+use CodeIgniter\Test\CIUnitTestCase;
+use CodeIgniter\Test\StreamFilterTrait;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * @internal
+ */
+#[Group('Others')]
+final class NullInputOutputTest extends CIUnitTestCase
+{
+    use StreamFilterTrait;
+
+    public function testFwriteDiscardsOutput(): void
+    {
+        $io = new NullInputOutput();
+        $io->fwrite(STDOUT, 'should not appear');
+        $io->fwrite(STDERR, 'should not appear either');
+
+        $this->assertSame('', $this->getStreamFilterBuffer());
+    }
+
+    public function testInputReturnsEmptyStringWithoutEchoingPrefix(): void
+    {
+        $io = new NullInputOutput();
+
+        $this->assertSame('', $io->input());
+        $this->assertSame('', $io->input('any prefix > '));
+        $this->assertSame('', $this->getStreamFilterBuffer());
+    }
+
+    public function testCanBeSwappedIntoCliToSilenceWrites(): void
+    {
+        $prior = CLI::getInputOutput();
+        CLI::setInputOutput(new NullInputOutput());
+
+        try {
+            CLI::write('this should be discarded');
+            CLI::error('this too');
+            $this->assertSame('', $this->getStreamFilterBuffer());
+        } finally {
+            if ($prior instanceof InputOutput) {
+                CLI::setInputOutput($prior);
+            } else {
+                CLI::resetInputOutput();
+            }
+        }
+    }
+}

user_guide_src/source/changelogs/v4.8.0.rst

@@ -193,6 +193,9 @@ Commands
   When used with ``CLI::getOption()``, an array option will return its last value (for example, in this case, ``value2``). To retrieve all values for an array option, use ``CLI::getRawOption()``.
 - Likewise, the ``command()`` function now also supports the above enhancements for command-line option parsing when using the function to run commands from code.
 - Added ``make:request`` generator command to scaffold :ref:`Form Request <form-requests>` classes.
+- Added ``AbstractCommand::callSilently()`` to invoke another command with its output discarded, restoring the prior IO afterwards. See :ref:`modern-commands-call-silently`.
+- Added :php:class:`NullInputOutput <CodeIgniter\\CLI\\NullInputOutput>`, an :php:class:`InputOutput <CodeIgniter\\CLI\\InputOutput>` sink that discards all writes and returns an empty string from ``input()``.
+- Added ``CLI::getInputOutput()`` (``@internal``) as a getter symmetric to ``CLI::setInputOutput()`` and ``CLI::resetInputOutput()``.
 
 Testing
 =======

user_guide_src/source/cli/cli_modern_commands.rst

@@ -273,6 +273,21 @@ To forward the caller's own input through to the target command, pass
 
 .. literalinclude:: cli_modern_commands/008.php
 
+.. _modern-commands-call-silently:
+
+Calling Silently
+================
+
+When a command delegates a step to another command but wants to emit its own
+consolidated message instead of letting the sub-command's output leak through,
+use ``$this->callSilently()``:
+
+.. literalinclude:: cli_modern_commands/012.php
+
+The sub-command's output is suppressed and ``$noInteractionOverride`` defaults
+to ``true``, since a silenced sub-command cannot meaningfully prompt. Pass an
+explicit value to override.
+
 **************
 Usage Examples
 **************
@@ -546,6 +561,16 @@ covered in the sections above and are not listed here.
         Invokes another modern command. The arguments and options go through
         bind and validate on the target command, just like a user invocation.
 
+    .. php:method:: callSilently(string $command[, array $arguments = [], array $options = [], ?bool $noInteractionOverride = true]): int
+
+        :param string    $command:                The name of the modern command to call.
+        :param array     $arguments:              Positional arguments to forward.
+        :param array     $options:                Options to forward, keyed by long name, shortcut, or negation.
+        :param bool|null $noInteractionOverride:  See :php:meth:`call`. Defaults to ``true``.
+        :returns:                                 The exit code returned by the called command.
+
+        Like :php:meth:`call`, but suppresses the sub-command's output.
+
     .. php:method:: getUnboundArguments(): array
 
         Returns the raw, parsed positional arguments as passed to the

user_guide_src/source/cli/cli_modern_commands/012.php

@@ -0,0 +1,12 @@
+<?php
+
+use CodeIgniter\CLI\CLI;
+
+// Inside execute():
+
+// Run `cache:clear` without leaking its own output; emit our own message instead.
+$exitCode = $this->callSilently('cache:clear');
+
+if ($exitCode === EXIT_SUCCESS) {
+    CLI::write('Cache cleared as part of deploy step.', 'green');
+}