diff --git a/package.json b/package.json
index 6ad3ab4..c3dfad0 100644
--- a/package.json
+++ b/package.json
@@ -33,8 +33,8 @@
     "eslint": "npm run safe_bazelisk test polygerrit-ui/app:lint_test",
     "eslintfix": "npm run safe_bazelisk run polygerrit-ui/app:lint_bin -- -- --fix $(pwd)/polygerrit-ui/app",
     "polylint": "npm run safe_bazelisk test polygerrit-ui/app:polylint_test",
-    "test:debug": "npm run compile:local && npm run safe_bazelisk run //polygerrit-ui:karma_bin -- -- start $(pwd)/polygerrit-ui/karma.conf.js --browsers ChromeDev --no-single-run --testFiles",
-    "test:single": "npm run compile:local && npm run safe_bazelisk run //polygerrit-ui:karma_bin -- -- start $(pwd)/polygerrit-ui/karma.conf.js --testFiles",
+    "test:debug": "npm run compile:local && npm run safe_bazelisk run //polygerrit-ui:karma_bin -- -- start $(pwd)/polygerrit-ui/karma.conf.js --root '.ts-out/polygerrit-ui/app/' --browsers ChromeDev --no-single-run --test-files",
+    "test:single": "npm run compile:local && npm run safe_bazelisk run //polygerrit-ui:karma_bin -- -- start $(pwd)/polygerrit-ui/karma.conf.js --root '.ts-out/polygerrit-ui/app/' --test-files",
     "postinstall": "(git apply --reverse --ignore-whitespace twinkie.patch || true) && git apply --ignore-whitespace twinkie.patch",
     "polytest": "npm run safe_bazelisk test //polygerrit-ui/app:validate_polymer_templates",
     "polytest:dev": "rm -rf ./polygerrit-ui/app/tmpl_out && npm run safe_bazelisk build //polygerrit-ui/app:template_test_tar && mkdir ./polygerrit-ui/app/tmpl_out && tar -xf bazel-bin/polygerrit-ui/app/template_test_tar.tar -C ./polygerrit-ui/app/tmpl_out"
diff --git a/polygerrit-ui/BUILD b/polygerrit-ui/BUILD
index 7bca96d..62d1d92 100644
--- a/polygerrit-ui/BUILD
+++ b/polygerrit-ui/BUILD
@@ -1,5 +1,6 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary")
 load("//tools/bzl:genrule2.bzl", "genrule2")
+load("//tools/bzl:js.bzl", "karma_test")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -33,8 +34,6 @@
     ],
 )
 
-# Define a karma+plugins binary to run karma-mocha tests.
-# Can be reused multiple time, if there are multiple karma test rules
 sh_binary(
     name = "karma_bin",
     srcs = ["@ui_dev_npm//:node_modules/karma/bin/karma"],
@@ -49,26 +48,8 @@
     ],
 )
 
-# Run all tests in one.
-# TODO(dmfilippov): allow parallel tests for karma - either on the bazel level
-# or on the karma level. For now single sh_test is enough.
-sh_test(
+karma_test(
     name = "karma_test",
-    size = "enormous",
     srcs = ["karma_test.sh"],
-    args = [
-        "$(location :karma_bin)",
-        "$(location karma.conf.js)",
-    ],
-    data = [
-        "karma.conf.js",
-        ":karma_bin",
-        "//polygerrit-ui/app:test-srcs-fg",
-    ],
-    # Should not run sandboxed.
-    tags = [
-        "karma",
-        "local",
-        "manual",
-    ],
+    data = ["//polygerrit-ui/app:test-srcs-fg"],
 )
diff --git a/polygerrit-ui/karma.conf.js b/polygerrit-ui/karma.conf.js
index 00ebc63..a3b694f 100644
--- a/polygerrit-ui/karma.conf.js
+++ b/polygerrit-ui/karma.conf.js
@@ -22,6 +22,7 @@
   if(runUnderBazel) {
     // Run under bazel
     return [
+      `external/plugins_npm/node_modules`,
       `external/ui_npm/node_modules`,
       `external/ui_dev_npm/node_modules`
     ];
@@ -58,11 +59,11 @@
 }
 
 module.exports = function(config) {
-  const localDirName = path.resolve(__dirname, '../.ts-out/polygerrit-ui/app');
-  const rootDir = runUnderBazel ?
-      'polygerrit-ui/app/_pg_with_tests_out/' : localDirName + '/';
-  const testFilesLocationPattern =
-      `${rootDir}**/!(template_test_srcs)/`;
+  let root = config.root;
+  if (!root) {
+    console.warn(`--root argument not set. Falling back to __dirname.`)
+    root = path.resolve(__dirname) + '/';
+  }
   // Use --test-files to specify pattern for a test files.
   // It can be just a file name, without a path:
   // --test-files async-foreach-behavior_test.js
@@ -83,7 +84,9 @@
   } else {
     filePattern = '*_test.js';
   }
-  const testFilesPattern = testFilesLocationPattern + filePattern;
+  const testFilesPattern = root + '**/' + filePattern;
+
+  console.info(`Karma test file pattern: ${testFilesPattern}`)
   // Special patch for grep parameters (see details in the grep-patch-karam.js)
   const additionalFiles = runUnderBazel ? [] : ['polygerrit-ui/grep-patch-karma.js'];
   config.set({
diff --git a/polygerrit-ui/karma_test.sh b/polygerrit-ui/karma_test.sh
index 5fab442..940b969 100755
--- a/polygerrit-ui/karma_test.sh
+++ b/polygerrit-ui/karma_test.sh
@@ -1,4 +1,6 @@
 #!/bin/bash
 
 set -euo pipefail
-./$1 start $2 --single-run
+./$1 start $2 \
+  --root 'polygerrit-ui/app/_pg_with_tests_out/**/' \
+  --test-files '*_test.js'
diff --git a/tools/bzl/js.bzl b/tools/bzl/js.bzl
index eedf0a1..c8d6e4b 100644
--- a/tools/bzl/js.bzl
+++ b/tools/bzl/js.bzl
@@ -142,3 +142,36 @@
             "zip -Drq $$ROOT/$@ -g .",
         ]),
     )
+
+def karma_test(name, srcs, data):
+    """Creates a Karma test target.
+
+    It can be used both for the main Gerrit js bundle, but also for plugins. So
+    it should be extremely easy to add Karma test capabilities for new plugins.
+
+    We are sharing one karma.conf.js file. If you want to customize that, then
+    consider using command line arguments that the config file can process, see
+    the `root` argument for an example.
+
+    Args:
+      name: The name of the test rule.
+      srcs: The shell script to invoke, where you can set command line
+        arguments for Karma and its config.
+      data: The bundle of JavaScript files with the tests included.
+    """
+
+    native.sh_test(
+        name = name,
+        size = "enormous",
+        srcs = srcs,
+        args = [
+            "$(location //polygerrit-ui:karma_bin)",
+            "$(location //polygerrit-ui:karma.conf.js)",
+        ],
+        data = data + [
+            "//polygerrit-ui:karma_bin",
+            "//polygerrit-ui:karma.conf.js",
+        ],
+        # Should not run sandboxed.
+        tags = ["karma", "local", "manual"],
+    )
diff --git a/tools/js/eslint.bzl b/tools/js/eslint.bzl
index b32e2bc..eb4d37a 100644
--- a/tools/js/eslint.bzl
+++ b/tools/js/eslint.bzl
@@ -16,6 +16,34 @@
 
 load("@build_bazel_rules_nodejs//:index.bzl", "nodejs_binary", "nodejs_test")
 
+def plugin_eslint():
+    """ Convenience wrapper macro of eslint() for Gerrit js plugins
+
+    Args:
+        name: name of the rule
+    """
+    eslint(
+        name = "lint",
+        srcs = native.glob(["**/*.ts"]),
+        config = ".eslintrc.js",
+        data = [
+            "tsconfig.json",
+            "//plugins:.eslintrc.js",
+            "//plugins:.prettierrc.js",
+            "//plugins:tsconfig-plugins-base.json",
+        ],
+        extensions = [".ts"],
+        ignore = "//plugins:.eslintignore",
+        plugins = [
+            "@npm//eslint-config-google",
+            "@npm//eslint-plugin-html",
+            "@npm//eslint-plugin-import",
+            "@npm//eslint-plugin-jsdoc",
+            "@npm//eslint-plugin-prettier",
+            "@npm//gts",
+        ],
+    )
+
 def eslint(name, plugins, srcs, config, ignore, extensions = [".js"], data = []):
     """ Macro to define eslint rules for files.
 
@@ -87,7 +115,7 @@
             "*_test_require_patch.js",
             "--ignore-pattern",
             "*_test_loader.js",
-            "./", # Relative to the config file location
+            "./",  # Relative to the config file location
         ],
         # Should not run sandboxed.
         tags = [