devtool: Add test-image plugin for testing packages via devtool via images.

diff --git a/meta/lib/oeqa/selftest/cases/devtool.py b/meta/lib/oeqa/selftest/cases/devtool.py
index d1209dd94e..c27934a3ca 100644
--- a/meta/lib/oeqa/selftest/cases/devtool.py
+++ b/meta/lib/oeqa/selftest/cases/devtool.py
@@ -1932,6 +1932,67 @@  class DevtoolBuildImageTests(DevtoolBase):
         if reqpkgs:
             self.fail('The following packages were not present in the image as expected: %s' % ', '.join(reqpkgs))
 
+
+class DevtoolTestImageTests(DevtoolBase):
+
+    @OETestTag("runqemu")
+    def test_devtool_test_image(self):
+        """Test devtool test-image plugin."""
+
+        machine = get_bb_var('MACHINE')
+        if not machine or not machine.startswith('qemu'):
+            self.skipTest('This test only works with qemu machines')
+
+        self.assertTrue(not os.path.exists(self.workspacedir),
+                        'This test cannot be run with a workspace directory under the build directory')
+
+        image = 'oe-selftest-image'
+        recipe = 'python3-atomicwrites'
+
+        # Ensure selected test package is ptest-capable.
+        ptest_path = get_bb_var('PTEST_PATH', recipe)
+        self.assertTrue(ptest_path,
+                'Selected package %s does not appear to inherit ptest' % recipe)
+
+        self.track_for_cleanup(self.workspacedir)
+        # self.add_command_to_tearDown('bitbake -c clean %s' % image)
+        self.add_command_to_tearDown('bitbake-layers remove-layer */workspace')
+
+        # Ensure we're starting from a clean state
+        bitbake('%s -c clean' % image)
+
+        result = runCmd('devtool test-image %s -p %s' % (image, recipe), ignore_status=True)
+        if result.status != 0 and 'runqemu - ERROR - Unknown path arg' in result.output:
+            self.skipTest('runqemu in this environment does not accept testimage rootfs path args')
+        self.assertEqual(result.status, 0,
+                         'devtool test-image failed unexpectedly:\n%s' % result.output)
+
+        # Check that requested package and its ptest package were installed
+        deploy_dir_image = get_bb_var('DEPLOY_DIR_IMAGE')
+        self.assertTrue(deploy_dir_image, 'Unable to get DEPLOY_DIR_IMAGE')
+
+        manifests = sorted(glob.glob(os.path.join(deploy_dir_image, '%s*.manifest' % image)))
+        self.assertTrue(manifests, 'Image manifest not found for %s in %s' % (image, deploy_dir_image))
+        manifest = manifests[-1]
+        self.assertExists(manifest, 'Image manifest not found: %s' % manifest)
+
+        pkgs = set()
+        with open(manifest, 'r') as f:
+            for line in f:
+                splitval = line.split()
+                if splitval:
+                    pkgs.add(splitval[0])
+
+        self.assertIn(recipe, pkgs)
+        self.assertIn(recipe + '-ptest', pkgs)
+
+        match = re.search(r'Logs are in (\S+)', result.output)
+        if match:
+            logdir = match.group(1)
+        else:
+            logdir = os.path.join(self.workspacedir, 'testimage-logs')
+        self.assertTrue(os.path.isdir(logdir), 'Expected logs directory not found: %s' % logdir)
+
 class DevtoolUpgradeTests(DevtoolBase):
 
     def setUp(self):
diff --git a/scripts/lib/devtool/test_image.py b/scripts/lib/devtool/test_image.py
new file mode 100644
index 0000000000..45d5931ae6
--- /dev/null
+++ b/scripts/lib/devtool/test_image.py
@@ -0,0 +1,130 @@ 
+# Development tool - test-image plugin
+#
+# Copyright (C) 2026 Authors
+#
+# SPDX-License-Identifier: GPL-2.0-only
+
+"""Devtool plugin containing the test-image subcommand.
+
+Builds a target image, installs specified package(s) from the workspace or
+layer, and runs the image's test suite via the BitBake `testimage` task.
+"""
+
+import os
+import logging
+
+from devtool import DevtoolError
+from devtool.build_image import build_image_task
+
+logger = logging.getLogger('devtool')
+
+
+def _create_ptest_recipe_appends(config, package_names):
+    """Create temporary per-package appends forcing PTEST_ENABLED=1.
+
+    Returns list of created file paths for cleanup.
+    """
+    created = []
+    appends_dir = os.path.join(config.workspace_path, 'appends')
+    os.makedirs(appends_dir, exist_ok=True)
+
+    for pn in sorted(set(package_names)):
+        appendfile = os.path.join(appends_dir, f'{pn}_%.bbappend')
+        if os.path.exists(appendfile):
+            logger.debug('Using existing append %s', appendfile)
+            continue
+        with open(appendfile, 'w') as afile:
+            afile.write('PTEST_ENABLED = "1"\n')
+        created.append(appendfile)
+
+    return created
+
+
+def test_image(args, config, basepath, workspace):
+    """Entry point for the devtool 'test-image' subcommand."""
+
+    if not args.imagename:
+        raise DevtoolError('Image recipe to test must be specified')
+    if not args.package:
+        raise DevtoolError('Package(s) to install must be specified via -p/--package')
+
+    package_names = [p.strip() for p in args.package.split(',') if p.strip()]
+    if not package_names:
+        raise DevtoolError('No valid package name(s) provided')
+
+    install_pkgs = package_names
+
+    logdir = os.path.join(config.workspace_path, 'testimage-logs')
+    try:
+        os.makedirs(logdir, exist_ok=True)
+    except Exception as exc:
+        raise DevtoolError(f'Failed to create test logs directory {logdir}: {exc}')
+
+    pkg_append = ' '.join(sorted(set(install_pkgs)))
+    extra_append = [
+        f'TEST_LOG_DIR = "{logdir}"',
+        # Ensure runtime test framework is enabled even if image/distro omitted it
+        'IMAGE_CLASSES += " testimage"',
+        # Ensure the testimage task has the correct IMAGE_FEATURES set in case the TEST_TARGET is qemu
+        'IMAGE_FEATURES += "allow-empty-password empty-root-password allow-root-login"',
+        'TEST_SUITES = " ping ssh ptest"',
+        'TEST_RUNQEMUPARAMS += "slirp"',
+        # Ensure image artifacts are built before do_testimage reads them.
+        'do_testimage[depends] += " ${PN}:do_image_complete virtual/kernel:do_deploy"',
+        # Ensure rootfs link naming is runqemu-compatible for image names that
+        # otherwise end with '-image' (without a trailing '-').
+        'IMAGE_LINK_NAME = "${IMAGE_BASENAME}-${MACHINE}"',
+        # Ensure a qemu-supported rootfs type is built/selected
+        'IMAGE_FSTYPES:append = " ext4"',
+        'QB_DEFAULT_FSTYPE = "ext4"',
+        # Enable ptests and include available -ptest packages for installed content
+        'DISTRO_FEATURES:append = " ptest"',
+        'IMAGE_FEATURES += " ptest-pkgs"',
+        'IMAGE_INSTALL:append = " ptest-runner dropbear"',
+        # Ensure requested packages (and -ptest where available) are installed
+        f'IMAGE_INSTALL:append = " {pkg_append}"',
+    ]
+
+    temp_ptest_appends = _create_ptest_recipe_appends(config, package_names)
+
+    logger.info('Running testimage for %s with packages: %s',
+                args.imagename, ' '.join(install_pkgs))
+    try:
+        result, _outputdir = build_image_task(
+            config,
+            basepath,
+            workspace,
+            args.imagename,
+            add_packages=None,
+            task='testimage',
+            extra_append=extra_append,
+        )
+    finally:
+        for appendfile in temp_ptest_appends:
+            if os.path.exists(appendfile):
+                os.unlink(appendfile)
+
+    if result == 0:
+        logger.info('Testimage completed. Logs are in %s', logdir)
+    return result
+
+
+def register_commands(subparsers, context):
+    """Register devtool subcommands from the test-image plugin"""
+    parser = subparsers.add_parser(
+        'test-image',
+        help='Build image, install package(s), and run testimage',
+        description=(
+            'Builds an image, installs specified package(s), and runs the\n'
+            'BitBake testimage task to validate on-target functionality.'
+        ),
+        group='testbuild',
+        order=-9,
+    )
+    parser.add_argument('imagename', help='Image recipe to test')
+    parser.add_argument(
+        '-p', '--package', '--packages',
+        help='Package(s) to install into the image (comma-separated)',
+        metavar='PACKAGES',
+    )
+    parser.set_defaults(func=test_image)