diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8edfff05c8c..89da7ec2a4a 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -91,6 +91,23 @@ jobs:
         with:
           name: coverage
           path: coverage
+  
+  test-deno:
+    runs-on: ubuntu-latest
+    name: Deno tests
+    steps:
+      - uses: actions/checkout@2541b1294d2704b0964813337f33b291d3f8596b # v3.0.2
+      - name: Setup node
+        uses: actions/setup-node@2fddd8803e2f5c9604345a0b591c3020ee971a93 # v3.4.1
+        with:
+          node-version: 16
+      - name: Setup Deno
+        uses: actions/setup-deno #v1
+        with:
+          deno-version: v1.25.x
+      - run: npm install
+      - name: Run Deno tests
+        run: npm run test-deno
 
   test-replica-sets:
     needs:
diff --git a/lib/schematype.js b/lib/schematype.js
index 0cc6c3eea59..837719a32a9 100644
--- a/lib/schematype.js
+++ b/lib/schematype.js
@@ -56,7 +56,7 @@ function SchemaType(path, options, instance) {
   const defaultOptionsKeys = Object.keys(defaultOptions);
 
   for (const option of defaultOptionsKeys) {
-    if (defaultOptions.hasOwnProperty(option) && !options.hasOwnProperty(option)) {
+    if (defaultOptions.hasOwnProperty(option) && !Object.prototype.hasOwnProperty.call(options, option)) {
       options[option] = defaultOptions[option];
     }
   }
diff --git a/package.json b/package.json
index 2767c008775..3360a3ccc8c 100644
--- a/package.json
+++ b/package.json
@@ -94,6 +94,7 @@
     "release-legacy": "git pull origin 5.x && git push origin 5.x --tags && npm publish --tag legacy",
     "mongo": "node ./tools/repl.js",
     "test": "mocha --exit ./test/*.test.js",
+    "test-deno": "deno run --allow-env --allow-read --allow-net --allow-run --unstable ./test/deno.js",
     "test-rs": "START_REPLICA_SET=1 mocha --timeout 30000 --exit ./test/*.test.js",
     "test-tsd": "node ./test/types/check-types-filename && tsd",
     "tdd": "mocha ./test/*.test.js --inspect --watch --recursive --watch-files ./**/*.{js,ts}",
diff --git a/test/deno.js b/test/deno.js
new file mode 100644
index 00000000000..a13618ae410
--- /dev/null
+++ b/test/deno.js
@@ -0,0 +1,33 @@
+'use strict';
+
+import { createRequire } from "https://deno.land/std/node/module.ts";
+
+import { parse } from "https://deno.land/std/flags/mod.ts"
+const args = parse(Deno.args);
+
+const require = createRequire(import.meta.url);
+
+const Mocha = require('mocha');
+const fs = require('fs');
+const path = require('path');
+
+const mocha = new Mocha({
+  ...(args.g ? { fgrep: '' + args.g } : {})
+});
+
+const testDir = 'test';
+const files = fs.readdirSync(testDir);
+
+const ignoreFiles = new Set(['browser.test.js', 'connection.test.js', 'index.test.js']);
+
+for (const file of files) {
+  if (!file.endsWith('.test.js') || ignoreFiles.has(file)) {
+    continue;
+  }
+
+  mocha.addFile(path.join(testDir, file));
+}
+
+mocha.run(function(failures) {
+  process.exitCode = failures ? 1 : 0;  // exit with non-zero status if there were failures
+});
\ No newline at end of file
diff --git a/test/docs/lean.test.js b/test/docs/lean.test.js
index 49cd0c45aad..576d8bcdcf3 100644
--- a/test/docs/lean.test.js
+++ b/test/docs/lean.test.js
@@ -1,7 +1,6 @@
 'use strict';
 
 const assert = require('assert');
-const v8Serialize = require('v8').serialize;
 const start = require('../common');
 
 // This file is in `es-next` because it uses async/await for convenience
@@ -23,6 +22,12 @@ describe('Lean Tutorial', function() {
   });
 
   it('compare sizes lean vs not lean', async function() {
+    // acquit:ignore:start
+    if (typeof Deno !== 'undefined') {
+      return this.skip(); // Deno does not support v8.serialize()
+    }
+    const v8Serialize = require('v8').serialize;
+    // acquit:ignore:end
     const schema = new mongoose.Schema({ name: String });
     const MyModel = mongoose.model('Test', schema);
 
diff --git a/test/query.test.js b/test/query.test.js
index d357d256001..fc1ad0b4080 100644
--- a/test/query.test.js
+++ b/test/query.test.js
@@ -2339,6 +2339,13 @@ describe('Query', function() {
       });
 
       it('throw on sync exceptions in callbacks (gh-6178)', function(done) {
+        // Deno doesn't support 'uncaughtException', so there's no way to test this in Deno
+        // without starting a separate process.
+        // See: https://stackoverflow.com/questions/64871554/deno-how-to-handle-exceptions
+        if (typeof Deno !== 'undefined') {
+          return this.skip();
+        }
+
         const schema = new Schema({});
         const Test = db.model('Test', schema);
 
diff --git a/test/schema.subdocumentpath.test.js b/test/schema.subdocumentpath.test.js
index d7a131ab5c3..60d4a1e2f3c 100644
--- a/test/schema.subdocumentpath.test.js
+++ b/test/schema.subdocumentpath.test.js
@@ -179,7 +179,7 @@ describe('SubdocumentPath', function() {
     assert.ok(err);
     assert.ok(err.errors['nested']);
 
-    mongoose.Schema.Types.Subdocument.set('required', false);
+    delete mongoose.Schema.Types.Subdocument.defaultOptions.required;
   });
 
   it('supports setting _id globally (gh-11541) (gh-8883)', function() {
@@ -197,6 +197,5 @@ describe('SubdocumentPath', function() {
     assert.ok(!doc.nested._id);
 
     delete mongoose.Schema.Types.Subdocument.defaultOptions._id;
-    mongoose.Schema.Types.Subdocument.set('required', false);
   });
 });
diff --git a/test/schema.test.js b/test/schema.test.js
index c09895de3b3..0a994b87398 100644
--- a/test/schema.test.js
+++ b/test/schema.test.js
@@ -1178,6 +1178,11 @@ describe('schema', function() {
 
   describe('other contexts', function() {
     it('work', function(done) {
+      if (typeof Deno !== 'undefined') {
+        // Deno throws "Not implemented: Script.prototype.runInNewContext"
+        return this.skip();
+      }
+
       const str = 'code = {' +
         '  name: String' +
         ', arr1: Array ' +
diff --git a/test/schematype.test.js b/test/schematype.test.js
index 6b96bde4377..6e07390a2bc 100644
--- a/test/schematype.test.js
+++ b/test/schematype.test.js
@@ -224,6 +224,8 @@ describe('schematype', function() {
 
         // Assert
         assert.equal(schema.path('test').options.someRandomOption, true);
+
+        delete type.defaultOptions.someRandomOption;
       });
     });
   });