diff --git a/packages/html2/jest.config.ts b/packages/html2/jest.config.ts
new file mode 100644
index 0000000..580f2eb
--- /dev/null
+++ b/packages/html2/jest.config.ts
@@ -0,0 +1,7 @@
+/// SPDX-License-Identifier: GPL-3.0-or-later
+/// SPDX-FileCopyrightText: Copyright © 2016-2024 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
+
+export default {
+  preset: 'ts-jest',
+  testEnvironment: './patched-jsdom.mjs',
+};
diff --git a/packages/html2/package.json b/packages/html2/package.json
index 16d0e62..b407c6d 100644
--- a/packages/html2/package.json
+++ b/packages/html2/package.json
@@ -22,7 +22,9 @@
     "rollup": "rollup -c",
     "rollup:watch": "rollup -c -w",
     "clean": "rm -rf lib/ dist/ index.js index.js.map",
-    "veryclean": "yarn run clean && rm -rf node_modules"
+    "veryclean": "yarn run clean && rm -rf node_modules",
+    "test": "../../node_modules/.bin/jest",
+    "test:watch": "yarn test --watch"
   },
   "dependencies": {
     "@syndicate-lang/core": "^0.34.8"
diff --git a/packages/html2/patched-jsdom.mjs b/packages/html2/patched-jsdom.mjs
new file mode 100644
index 0000000..52d3dde
--- /dev/null
+++ b/packages/html2/patched-jsdom.mjs
@@ -0,0 +1,14 @@
+/// SPDX-License-Identifier: GPL-3.0-or-later
+/// SPDX-FileCopyrightText: Copyright © 2024 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
+
+// https://github.com/jsdom/jsdom/issues/2524
+
+import { TextEncoder, TextDecoder } from 'util';
+import $JSDOMEnvironment from 'jest-environment-jsdom';
+export default class JSDOMEnvironment extends $JSDOMEnvironment {
+  constructor(... args) {
+    const { global } = super(... args);
+    if (!global.TextEncoder) global.TextEncoder = TextEncoder;
+    if (!global.TextDecoder) global.TextDecoder = TextDecoder;
+  }
+}
diff --git a/packages/html2/test/html.test.ts b/packages/html2/test/html.test.ts
new file mode 100644
index 0000000..a0ae91f
--- /dev/null
+++ b/packages/html2/test/html.test.ts
@@ -0,0 +1,47 @@
+/// SPDX-License-Identifier: GPL-3.0-or-later
+/// SPDX-FileCopyrightText: Copyright © 2024 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
+
+import { template } from '../src/html';
+import './test-utils';
+
+describe('basic templating', () => {
+    it('should produce a node', () => {
+        const x = document.createElement('x');
+        x.appendChild(document.createTextNode('y'));
+        expect(template()`<x>y</x>`).toEqual([x]);
+    });
+
+    it('should substitute a string', () => {
+        const x = document.createElement('x');
+        const y = 'abc';
+        x.appendChild(document.createTextNode('abc'));
+        expect('' + template()`<x>${y}</x>`).toEqual('' + [x]);
+    });
+
+    it('should substitute a node', () => {
+        const x = document.createElement('x');
+        const z = document.createElement('z');
+        z.appendChild(document.createTextNode('q'));
+        x.appendChild(z);
+        const y = template()`<z>q</z>`;
+        expect('' + template()`<x>${y}</x>`).toEqual('' + [x]);
+    });
+
+    it('should substitute an array of strings', () => {
+        const x = document.createElement('x');
+        const y = ['abc', 'def'];
+        x.appendChild(document.createTextNode('abcdef'));
+        expect('' + template()`<x>${y}</x>`).toEqual('' + [x]);
+    });
+
+    it('should substitute an array of strings and nodes', () => {
+        const x = document.createElement('x');
+        const y = ['abc', template()`<z>q</z>`, 'def'];
+        const z = document.createElement('z');
+        z.appendChild(document.createTextNode('q'));
+        x.appendChild(document.createTextNode('abc'));
+        x.appendChild(z);
+        x.appendChild(document.createTextNode('def'));
+        expect('' + template()`<x>${y}</x>`).toEqual('' + [x]);
+    });
+});
diff --git a/packages/html2/test/test-utils.ts b/packages/html2/test/test-utils.ts
new file mode 100644
index 0000000..ef7c81e
--- /dev/null
+++ b/packages/html2/test/test-utils.ts
@@ -0,0 +1,38 @@
+/// SPDX-License-Identifier: GPL-3.0-or-later
+/// SPDX-FileCopyrightText: Copyright © 2016-2024 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
+
+import { is, preserves } from '@preserves/core';
+
+declare global {
+    namespace jest {
+        interface Matchers<R> {
+            is(expected: any): R;
+            toThrowFilter(f: (e: Error) => boolean): R;
+        }
+    }
+}
+
+expect.extend({
+    is(actual, expected) {
+        return is(actual, expected)
+            ? { message: () => preserves`expected ${actual} not to be Preserves.is to ${expected}`,
+                pass: true }
+            : { message: () => preserves`expected ${actual} to be Preserves.is to ${expected}`,
+                pass: false };
+    },
+
+    toThrowFilter(thunk, f) {
+        try {
+            thunk();
+            return { message: () => preserves`expected an exception`, pass: false };
+        } catch (e) {
+            if (f(e)) {
+                return { message: () => preserves`expected an exception not matching the filter`,
+                         pass: true };
+            } else {
+                return { message: () => preserves`expected an exception matching the filter: ${(e as any)?.constructor?.name}`,
+                         pass: false };
+            }
+        }
+    }
+});