diff --git a/common/web/types/package.json b/common/web/types/package.json
index 4c2e2bfd2e..2b2122f682 100644
--- a/common/web/types/package.json
+++ b/common/web/types/package.json
@@ -36,8 +36,6 @@
     "restructure": "3.0.1"
   },
   "devDependencies": {
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "ajv": "^8.12.0",
     "ajv-cli": "^5.0.0",
     "ajv-formats": "^2.1.1",
diff --git a/developer/src/common/web/test-helpers/TestCompilerCallbacks.ts b/developer/src/common/web/test-helpers/TestCompilerCallbacks.ts
index 04e5734f18..711944f12d 100644
--- a/developer/src/common/web/test-helpers/TestCompilerCallbacks.ts
+++ b/developer/src/common/web/test-helpers/TestCompilerCallbacks.ts
@@ -5,6 +5,7 @@ import { CompilerEvent, CompilerCallbacks, CompilerPathCallbacks, CompilerFileSy
   CompilerFileSystemAsyncCallbacks,
   CompilerErrorSeverity} from '@keymanapp/developer-utils';
 import { fileURLToPath } from 'url';
+import { Suite } from 'mocha';
 
 const { TEST_SAVE_FIXTURES } = process.env;
 
@@ -12,16 +13,27 @@ const { TEST_SAVE_FIXTURES } = process.env;
  * A CompilerCallbacks implementation for testing
  */
 export class TestCompilerCallbacks implements CompilerCallbacks {
-  /* TestCompilerCallbacks */
-
+  private readonly suite: Suite;
   messages: CompilerEvent[] = [];
   readonly _net: TestCompilerNetAsyncCallbacks;
   readonly _fsAsync: DefaultCompilerFileSystemAsyncCallbacks = new DefaultCompilerFileSystemAsyncCallbacks(this);
 
-  constructor(basePath?: string) {
+  constructor(suite?: Suite, basePath?: string) {
     if(basePath) {
       this._net = new TestCompilerNetAsyncCallbacks(basePath);
     }
+    this.suite = suite;
+    if(this.suite) {
+      const _this = this;
+      this.suite.beforeEach(function() {
+        _this.clear();
+      });
+      this.suite.afterEach(function() {
+        if(this.currentTest?.isFailed()) {
+          _this.printMessages();
+        }
+      })
+    }
   }
 
   clear() {
@@ -55,7 +67,7 @@ export class TestCompilerCallbacks implements CompilerCallbacks {
 
   loadFile(filename: string): Uint8Array {
     try {
-      return fs.readFileSync(filename);
+      return fs.readFileSync(filename) as Uint8Array;
     } catch(e) {
       if (e.code === 'ENOENT') {
         return null;
@@ -162,7 +174,7 @@ class TestCompilerNetAsyncCallbacks implements CompilerNetAsyncCallbacks {
       // missing file, this is okay
       return null;
     }
-    const data: Uint8Array = fs.readFileSync(p);
+    const data = fs.readFileSync(p) as Uint8Array;
     return data;
   }
 
diff --git a/developer/src/common/web/utils/test/kpj/kpj-file-reader.tests.ts b/developer/src/common/web/utils/test/kpj/kpj-file-reader.tests.ts
index 358edb01da..a70d4dd42c 100644
--- a/developer/src/common/web/utils/test/kpj/kpj-file-reader.tests.ts
+++ b/developer/src/common/web/utils/test/kpj/kpj-file-reader.tests.ts
@@ -6,13 +6,15 @@ import { KPJFileReader } from "../../src/types/kpj/kpj-file-reader.js";
 import { KeymanDeveloperProjectFile10, KeymanDeveloperProjectType } from '../../src/types/kpj/keyman-developer-project.js';
 import { TestCompilerCallbacks } from '@keymanapp/developer-test-helpers';
 
-const callbacks = new TestCompilerCallbacks();
 
 describe('kpj-file-reader', function () {
+
+  const callbacks = new TestCompilerCallbacks(this);
+
   it('kpj-file-reader should read a valid file', async function() {
     const kpjPath = 'khmer_angkor.kpj';
     const path = makePathToFixture('kpj', kpjPath);
-    const input = fs.readFileSync(path);
+    const input = fs.readFileSync(path) as Uint8Array;
     const reader = new KPJFileReader(callbacks);
     const kpj = reader.read(input);
     reader.validate(kpj);
@@ -124,7 +126,7 @@ describe('kpj-file-reader', function () {
 
   it('should load a v1.0 keyboard project with missing <File>', async function() {
     const path = makePathToFixture('kpj', 'project-missing-file', 'project_missing_file.kpj');
-    const input = fs.readFileSync(path);
+    const input = fs.readFileSync(path) as Uint8Array;
     const reader = new KPJFileReader(callbacks);
     const kpj = reader.read(input);
     reader.validate(kpj);
@@ -140,7 +142,7 @@ describe('kpj-file-reader', function () {
 
   it('should load a v1.0 keyboard project with missing <Files>', async function() {
     const path = makePathToFixture('kpj', 'project-missing-file', 'project_missing_files.kpj');
-    const input = fs.readFileSync(path);
+    const input = fs.readFileSync(path) as Uint8Array;
     const reader = new KPJFileReader(callbacks);
     const kpj = reader.read(input);
     reader.validate(kpj);
diff --git a/developer/src/kmc-analyze/package.json b/developer/src/kmc-analyze/package.json
index c7e2ebabe2..432bb26e01 100644
--- a/developer/src/kmc-analyze/package.json
+++ b/developer/src/kmc-analyze/package.json
@@ -29,8 +29,6 @@
   },
   "devDependencies": {
     "@keymanapp/resources-gosh": "*",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "chalk": "^2.4.2",
     "typescript": "^5.4.5"
diff --git a/developer/src/kmc-copy/test/copier-messages.tests.ts b/developer/src/kmc-copy/test/copier-messages.tests.ts
index 0312910860..ea0e9bf624 100644
--- a/developer/src/kmc-copy/test/copier-messages.tests.ts
+++ b/developer/src/kmc-copy/test/copier-messages.tests.ts
@@ -14,17 +14,7 @@ import { KeymanProjectCopier } from '../src/KeymanProjectCopier.js';
 import { makePathToFixture } from './helpers/index.js';
 
 describe('CopierMessages', function () {
-  const callbacks = new TestCompilerCallbacks(makePathToFixture('online'));
-
-  this.beforeEach(function() {
-    callbacks.clear();
-  });
-
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed()) {
-      callbacks.printMessages();
-    }
-  });
+  const callbacks = new TestCompilerCallbacks(this, makePathToFixture('online'));
 
   it('should have a valid CopierMessages object', function() {
     return verifyCompilerMessagesObject(CopierMessages, CompilerErrorNamespace.Copier);
diff --git a/developer/src/kmc-copy/test/copier.tests.ts b/developer/src/kmc-copy/test/copier.tests.ts
index 697e58e0b5..2acf5bf12c 100644
--- a/developer/src/kmc-copy/test/copier.tests.ts
+++ b/developer/src/kmc-copy/test/copier.tests.ts
@@ -23,7 +23,7 @@ function normalizeNewLine(s: string): string {
 }
 
 describe('KeymanProjectCopier', function() {
-  const callbacks = new TestCompilerCallbacks(makePathToFixture('online'));
+  const callbacks = new TestCompilerCallbacks(this, makePathToFixture('online'));
 
   this.beforeAll(function() {
     if(TEST_SAVE_ARTIFACTS) {
@@ -32,16 +32,6 @@ describe('KeymanProjectCopier', function() {
     }
   });
 
-  this.beforeEach(function() {
-    callbacks.clear();
-  });
-
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed()) {
-      callbacks.printMessages();
-    }
-  });
-
   const tests = [
 
   //
diff --git a/developer/src/kmc-generate/test/lexical-model-generator.tests.ts b/developer/src/kmc-generate/test/lexical-model-generator.tests.ts
index 39908f25c9..f54dc5290c 100644
--- a/developer/src/kmc-generate/test/lexical-model-generator.tests.ts
+++ b/developer/src/kmc-generate/test/lexical-model-generator.tests.ts
@@ -35,6 +35,8 @@ function getFilenames(p: string, base?: string): string[] {
 describe('LexicalModelGenerator', function () {
   let clock: sinon.SinonFakeTimers;
 
+  const callbacks = new TestCompilerCallbacks(this);
+
   before(function() {
     // We will always be 12 April 2024 to match test fixtures
     clock = sinon.useFakeTimers(new Date(2024, 3, 12));
@@ -46,7 +48,6 @@ describe('LexicalModelGenerator', function () {
 
   it('should generate a lexical model from provided options', async function() {
     const generator = new LexicalModelGenerator();
-    const callbacks = new TestCompilerCallbacks();
     const opts: GeneratorOptions = {...options};
     opts.id = 'sample.en.sample';
     opts.targets = [KeymanTargets.KeymanTarget.any];
diff --git a/developer/src/kmc-keyboard-info/package.json b/developer/src/kmc-keyboard-info/package.json
index 5b0c463b3a..db256a6c78 100644
--- a/developer/src/kmc-keyboard-info/package.json
+++ b/developer/src/kmc-keyboard-info/package.json
@@ -29,8 +29,6 @@
     "@keymanapp/langtags": "*"
   },
   "devDependencies": {
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "chalk": "^2.4.2",
     "typescript": "^5.4.5"
diff --git a/developer/src/kmc-keyboard-info/test/keyboard-info-compiler-messages.tests.ts b/developer/src/kmc-keyboard-info/test/keyboard-info-compiler-messages.tests.ts
index fcd9dfb8c1..7bb355faef 100644
--- a/developer/src/kmc-keyboard-info/test/keyboard-info-compiler-messages.tests.ts
+++ b/developer/src/kmc-keyboard-info/test/keyboard-info-compiler-messages.tests.ts
@@ -8,8 +8,6 @@ import { makePathToFixture } from './helpers/index.js';
 import { KeyboardInfoCompiler } from '../src/keyboard-info-compiler.js';
 import { KeyboardInfoFile } from '../src/keyboard-info-file.js';
 
-const callbacks = new TestCompilerCallbacks();
-
 const KHMER_ANGKOR_JS  = makePathToFixture('khmer_angkor', 'build', 'khmer_angkor.js');
 const KHMER_ANGKOR_KPS = makePathToFixture('khmer_angkor', 'source', 'khmer_angkor.kps');
 const KHMER_ANGKOR_KMP = makePathToFixture('khmer_angkor', 'build', 'khmer_angkor.kmp');
@@ -24,15 +22,7 @@ const KHMER_ANGKOR_SOURCES = {
 
 describe('KeyboardInfoCompilerMessages', function () {
 
-  this.beforeEach(function() {
-    callbacks.clear();
-  });
-
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed()) {
-      callbacks.printMessages();
-    }
-  })
+  const callbacks = new TestCompilerCallbacks(this);
 
   it('should have a valid KeyboardInfoCompilerMessages object', function() {
     return verifyCompilerMessagesObject(KeyboardInfoCompilerMessages, CompilerErrorNamespace.KeyboardInfoCompiler);
diff --git a/developer/src/kmc-keyboard-info/test/keyboard-info-compiler.tests.ts b/developer/src/kmc-keyboard-info/test/keyboard-info-compiler.tests.ts
index 0bb17e539e..b9345e7508 100644
--- a/developer/src/kmc-keyboard-info/test/keyboard-info-compiler.tests.ts
+++ b/developer/src/kmc-keyboard-info/test/keyboard-info-compiler.tests.ts
@@ -10,18 +10,6 @@ import { KMX, KeymanFileTypes, KeymanTargets, KmpJsonFile } from '@keymanapp/com
 import { CompilerCallbacks } from '@keymanapp/developer-utils';
 import { KeyboardInfoFile, KeyboardInfoFileLanguage, KeyboardInfoFilePlatform } from './keyboard-info-file.js';
 
-const callbacks = new TestCompilerCallbacks();
-
-beforeEach(function() {
-  callbacks.clear();
-});
-
-afterEach(function() {
-  if(this.currentTest?.isFailed()) {
-    callbacks.printMessages();
-  }
-});
-
 const KHMER_ANGKOR_KPJ = makePathToFixture('khmer_angkor', 'khmer_angkor.kpj');
 const KHMER_ANGKOR_JS  = makePathToFixture('khmer_angkor', 'build', 'khmer_angkor.js');
 const KHMER_ANGKOR_KPS = makePathToFixture('khmer_angkor', 'source', 'khmer_angkor.kps');
@@ -87,6 +75,9 @@ const JAVA_DISPLAY_FONT_INFO = { family: "Java", source: [ JAVA_DISPLAY_FONT ] }
 const JAVA_OSK_FONT_INFO = { family: "Java Kbd", source: [ JAVA_OSK_FONT ] };
 
 describe('keyboard-info-compiler', function () {
+
+  const callbacks = new TestCompilerCallbacks(this);
+
   it('compile a .keyboard_info file correctly', async function() {
     const kpjFilename = KHMER_ANGKOR_KPJ;
     const buildKeyboardInfoFilename = makePathToFixture('khmer_angkor', 'build', 'khmer_angkor.keyboard_info');
@@ -844,6 +835,9 @@ describe('keyboard-info-compiler', function () {
 });
 
 describe('fillLanguageMetadata', function() {
+
+  const callbacks = new TestCompilerCallbacks(this);
+
   const tests: { bcp47: string, lang: KeyboardInfoFileLanguage, commonScript: string }[] = [
 
     // 'und' language subtag
diff --git a/developer/src/kmc-kmn/package.json b/developer/src/kmc-kmn/package.json
index f9c82fb4e9..88a172dfbb 100644
--- a/developer/src/kmc-kmn/package.json
+++ b/developer/src/kmc-kmn/package.json
@@ -32,8 +32,6 @@
   },
   "devDependencies": {
     "@keymanapp/developer-test-helpers": "*",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "@types/semver": "^7.3.12",
     "@types/sinon": "^10.0.13",
     "@types/sinon-chai": "^3.2.9",
diff --git a/developer/src/kmc-kmn/test/compiler.tests.ts b/developer/src/kmc-kmn/test/compiler.tests.ts
index cb190f519d..7b67e3dd58 100644
--- a/developer/src/kmc-kmn/test/compiler.tests.ts
+++ b/developer/src/kmc-kmn/test/compiler.tests.ts
@@ -11,6 +11,8 @@ const keyboardsDir = __dirname + '/../../../../../common/test/keyboards/';
 const baselineDir = keyboardsDir + 'baseline/';
 
 describe('Compiler class', function() {
+  const callbacks = new TestCompilerCallbacks(this);
+
   it('should throw on failure', async function() {
     const compiler = new KmnCompiler();
     const callbacks : any = null; // ERROR
@@ -25,14 +27,12 @@ describe('Compiler class', function() {
 
   it('should start', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
   });
 
   it('should compile a basic keyboard', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, {saveDebug: true, shouldAddCompilerVersion: false}));
     assert(compiler.verifyInitialized());
 
@@ -60,7 +60,6 @@ describe('Compiler class', function() {
   it('should build all baseline fixtures', async function() {
     this.timeout(10000); // there are quite a few fixtures, sometimes CI agents are slow
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, {saveDebug: true, shouldAddCompilerVersion: false}));
     assert(compiler.verifyInitialized());
 
@@ -90,7 +89,6 @@ describe('Compiler class', function() {
 
   it('should compile a keyboard with visual keyboard', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert.isTrue(await compiler.init(callbacks, {
       saveDebug: true,
       shouldAddCompilerVersion: false,
diff --git a/developer/src/kmc-kmn/test/features.tests.ts b/developer/src/kmc-kmn/test/features.tests.ts
index 1f82a03ed5..6d8f0bde19 100644
--- a/developer/src/kmc-kmn/test/features.tests.ts
+++ b/developer/src/kmc-kmn/test/features.tests.ts
@@ -7,19 +7,14 @@ import { KMX, KmxFileReader } from '@keymanapp/common-types';
 
 describe('Keyboard compiler features', function() {
   let compiler: KmnCompiler = null;
-  let callbacks: TestCompilerCallbacks = null;
+  const callbacks = new TestCompilerCallbacks(this);
 
   this.beforeAll(async function() {
     compiler = new KmnCompiler();
-    callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, {saveDebug: true}));
     assert(compiler.verifyInitialized());
   });
 
-  beforeEach(function() {
-    callbacks.clear();
-  });
-
   // Test each Keyman file version target
 
   const versions = [
diff --git a/developer/src/kmc-kmn/test/kmn-compiler-messages.tests.ts b/developer/src/kmc-kmn/test/kmn-compiler-messages.tests.ts
index 055535513d..f241c02606 100644
--- a/developer/src/kmc-kmn/test/kmn-compiler-messages.tests.ts
+++ b/developer/src/kmc-kmn/test/kmn-compiler-messages.tests.ts
@@ -7,7 +7,7 @@ import { KmnCompilerMessageRanges, KmnCompilerMessages } from '../src/compiler/k
 import { makePathToFixture } from './helpers/index.js';
 
 describe('KmnCompilerMessages', function () {
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   it('should have a valid KmnCompilerMessages object', function() {
     return verifyCompilerMessagesObject(KmnCompilerMessages, CompilerErrorNamespace.KmnCompiler);
diff --git a/developer/src/kmc-kmn/test/kmw/kmw-compiler.tests.ts b/developer/src/kmc-kmn/test/kmw/kmw-compiler.tests.ts
index a1008416aa..9fb4563d29 100644
--- a/developer/src/kmc-kmn/test/kmw/kmw-compiler.tests.ts
+++ b/developer/src/kmc-kmn/test/kmw/kmw-compiler.tests.ts
@@ -25,7 +25,7 @@ const generateTestFilenames = (id: string) => ({
 });
 
 describe('KeymanWeb Compiler', function() {
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
   const kmnCompiler: KmnCompiler = new KmnCompiler();
 
   this.beforeAll(async function() {
@@ -35,13 +35,6 @@ describe('KeymanWeb Compiler', function() {
     }));
   });
 
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed() || debug) {
-      callbacks.printMessages();
-    }
-    callbacks.clear();
-  });
-
   it('should compile a complex keyboard', async function() {
     await run_test_keyboard(kmnCompiler, 'khmer_angkor');
   });
diff --git a/developer/src/kmc-kmn/test/kmw/kmw-messages.tests.ts b/developer/src/kmc-kmn/test/kmw/kmw-messages.tests.ts
index a69db77020..175afdfe7a 100644
--- a/developer/src/kmc-kmn/test/kmw/kmw-messages.tests.ts
+++ b/developer/src/kmc-kmn/test/kmw/kmw-messages.tests.ts
@@ -7,7 +7,7 @@ import { KmnCompiler } from '../../src/main.js';
 import { CompilerErrorNamespace } from '@keymanapp/developer-utils';
 
 describe('KmwCompilerMessages', function () {
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   it('should have a valid KmwCompilerMessages object', function() {
     return verifyCompilerMessagesObject(KmwCompilerMessages, CompilerErrorNamespace.KmwCompiler);
diff --git a/developer/src/kmc-kmn/test/wasm-uset.tests.ts b/developer/src/kmc-kmn/test/wasm-uset.tests.ts
index ad67b35246..11a3e9a487 100644
--- a/developer/src/kmc-kmn/test/wasm-uset.tests.ts
+++ b/developer/src/kmc-kmn/test/wasm-uset.tests.ts
@@ -6,6 +6,8 @@ import { KmnCompilerMessages } from '../src/compiler/kmn-compiler-messages.js';
 import { compilerErrorFormatCode } from '@keymanapp/developer-utils';
 
 describe('Compiler UnicodeSet function', function() {
+  const callbacks = new TestCompilerCallbacks(this);
+
   it('should fixup "short" \\u{} escapes', function () {
     assert.equal(KmnCompiler.fixNewPattern(`\\u{A}`), `\\u000A`); // "
     assert.equal(KmnCompiler.fixNewPattern(`\\u{22}`), `\\u0022`); // "
@@ -24,14 +26,12 @@ describe('Compiler UnicodeSet function', function() {
 
   it('should start', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
   });
 
   it('should compile a basic uset', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
 
@@ -49,7 +49,6 @@ describe('Compiler UnicodeSet function', function() {
   });
   it('should compile a more complex uset', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
 
@@ -69,7 +68,6 @@ describe('Compiler UnicodeSet function', function() {
   });
   it('should compile an even more complex uset', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
 
@@ -96,7 +94,6 @@ describe('Compiler UnicodeSet function', function() {
   });
   it('should fail in various ways', async function() {
     const compiler = new KmnCompiler();
-    const callbacks = new TestCompilerCallbacks();
     assert(await compiler.init(callbacks, null));
     assert(compiler.verifyInitialized());
     // map from string to failing error
diff --git a/developer/src/kmc-ldml/package.json b/developer/src/kmc-ldml/package.json
index 9e2a1c6831..1a586eec78 100644
--- a/developer/src/kmc-ldml/package.json
+++ b/developer/src/kmc-ldml/package.json
@@ -35,8 +35,6 @@
     "@keymanapp/developer-test-helpers": "*",
     "@keymanapp/resources-gosh": "*",
     "@types/common-tags": "^1.8.4",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "@types/semver": "^7.3.12",
     "abnf": "^4.3.1",
     "c8": "^7.12.0",
diff --git a/developer/src/kmc-model-info/package.json b/developer/src/kmc-model-info/package.json
index c747a922c4..7d1e7f2fef 100644
--- a/developer/src/kmc-model-info/package.json
+++ b/developer/src/kmc-model-info/package.json
@@ -34,8 +34,6 @@
     "@keymanapp/developer-utils": "*"
   },
   "devDependencies": {
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "chalk": "^2.4.2",
     "typescript": "^5.4.5"
diff --git a/developer/src/kmc-model-info/test/model-info-compiler.tests.ts b/developer/src/kmc-model-info/test/model-info-compiler.tests.ts
index 4b0a85624e..5f87ad0f21 100644
--- a/developer/src/kmc-model-info/test/model-info-compiler.tests.ts
+++ b/developer/src/kmc-model-info/test/model-info-compiler.tests.ts
@@ -6,13 +6,9 @@ import { makePathToFixture } from './helpers/index.js';
 import { ModelInfoCompiler } from '../src/model-info-compiler.js';
 import { KmpCompiler } from '@keymanapp/kmc-package';
 
-const callbacks = new TestCompilerCallbacks();
-
-beforeEach(function() {
-  callbacks.clear();
-});
-
 describe('model-info-compiler', function () {
+  const callbacks = new TestCompilerCallbacks(this);
+
   it('compile a .model_info file correctly', async function() {
     const kpjFilename = makePathToFixture('sil.cmo.bw', 'sil.cmo.bw.model.kpj');
     const kpsFilename = makePathToFixture('sil.cmo.bw', 'source', 'sil.cmo.bw.model.kps');
diff --git a/developer/src/kmc-model/package.json b/developer/src/kmc-model/package.json
index 481822e686..52ef40c425 100644
--- a/developer/src/kmc-model/package.json
+++ b/developer/src/kmc-model/package.json
@@ -37,8 +37,6 @@
   "devDependencies": {
     "@keymanapp/developer-test-helpers": "*",
     "@keymanapp/models-templates": "*",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "chalk": "^2.4.2",
     "esbuild": "^0.25.0"
diff --git a/developer/src/kmc-model/test/compile-model-with-pseudoclosure.tests.ts b/developer/src/kmc-model/test/compile-model-with-pseudoclosure.tests.ts
index c4d3334b6a..6a8b55af7e 100644
--- a/developer/src/kmc-model/test/compile-model-with-pseudoclosure.tests.ts
+++ b/developer/src/kmc-model/test/compile-model-with-pseudoclosure.tests.ts
@@ -7,7 +7,7 @@ import { TestCompilerCallbacks } from '@keymanapp/developer-test-helpers';
 import { LexicalModelTypes } from '@keymanapp/common-types';
 
 describe('LexicalModelCompiler - pseudoclosure compilation + use', function () {
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   const MODEL_ID = 'example.qaa.trivial';
   const PATH = makePathToFixture(MODEL_ID);
diff --git a/developer/src/kmc-model/test/compile-model.tests.ts b/developer/src/kmc-model/test/compile-model.tests.ts
index e5c9e86c15..5c6a8ab104 100644
--- a/developer/src/kmc-model/test/compile-model.tests.ts
+++ b/developer/src/kmc-model/test/compile-model.tests.ts
@@ -7,7 +7,7 @@ import { TestCompilerCallbacks } from '@keymanapp/developer-test-helpers';
 import { KeymanFileTypes } from '@keymanapp/common-types';
 
 describe('LexicalModelCompiler', function () {
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   this.timeout(5000);
 
diff --git a/developer/src/kmc-model/test/compile-trie.tests.ts b/developer/src/kmc-model/test/compile-trie.tests.ts
index 81de56987e..24f05bb7ec 100644
--- a/developer/src/kmc-model/test/compile-trie.tests.ts
+++ b/developer/src/kmc-model/test/compile-trie.tests.ts
@@ -11,10 +11,7 @@ import { TrieModel } from '@keymanapp/models-templates';
 import { LexicalModelTypes } from '@keymanapp/common-types';
 
 describe('LexicalModelCompiler', function () {
-  const callbacks = new TestCompilerCallbacks();
-  this.beforeEach(function() {
-    callbacks.clear();
-  });
+  const callbacks = new TestCompilerCallbacks(this);
 
   describe('#generateLexicalModelCode', function () {
     it('should compile a trivial word list', async function () {
diff --git a/developer/src/kmc-model/test/messages.tests.ts b/developer/src/kmc-model/test/messages.tests.ts
index f9d3eb07b8..8d3bb10c08 100644
--- a/developer/src/kmc-model/test/messages.tests.ts
+++ b/developer/src/kmc-model/test/messages.tests.ts
@@ -8,17 +8,7 @@ import { makePathToFixture } from './helpers/index.js';
 
 describe('ModelCompilerMessages', function () {
 
-  const callbacks = new TestCompilerCallbacks();
-
-  this.beforeEach(function() {
-    callbacks.clear();
-  });
-
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed()) {
-      callbacks.printMessages();
-    }
-  });
+  const callbacks = new TestCompilerCallbacks(this);
 
   it('should have a valid ModelCompilerMessages object', function() {
     return verifyCompilerMessagesObject(ModelCompilerMessages, CompilerErrorNamespace.ModelCompiler);
diff --git a/developer/src/kmc-model/test/parse-wordlist.tests.ts b/developer/src/kmc-model/test/parse-wordlist.tests.ts
index ada01fbc2b..ba4f6cb92b 100644
--- a/developer/src/kmc-model/test/parse-wordlist.tests.ts
+++ b/developer/src/kmc-model/test/parse-wordlist.tests.ts
@@ -22,11 +22,10 @@ const SENCOTEN_WORDLIST = {
 
 
 describe('parsing a word list', function () {
-  const testCallbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   beforeEach(function () {
-    testCallbacks.clear();
-    setCompilerCallbacks(testCallbacks);
+    setCompilerCallbacks(callbacks);
   });
 
   afterEach(function () {
@@ -43,12 +42,12 @@ describe('parsing a word list', function () {
     const withoutBOM: WordList = {};
     parseWordListFromContents(withoutBOM, file);
     assert.deepEqual(withoutBOM, expected, "expected regular file to parse properly");
-    assert.isEmpty(testCallbacks.messages);
+    assert.isEmpty(callbacks.messages);
 
     const withBOM: WordList = {};
     parseWordListFromContents(withBOM, `${BOM}${file}`)
     assert.deepEqual(withBOM, expected, "expected BOM to be ignored");
-    assert.isEmpty(testCallbacks.messages);
+    assert.isEmpty(callbacks.messages);
   });
 
   it('should read word lists in UTF-8', function () {
@@ -58,7 +57,7 @@ describe('parsing a word list', function () {
     parseWordListFromFilename(wordlist, filename);
 
     assert.deepEqual(wordlist, SENCOTEN_WORDLIST);
-    assert.isEmpty(testCallbacks.messages);
+    assert.isEmpty(callbacks.messages);
   });
 
   it('should read word lists in UTF-16 little-endian (with BOM)', function () {
@@ -69,7 +68,7 @@ describe('parsing a word list', function () {
     parseWordListFromFilename(wordlist, filename);
 
     assert.deepEqual(wordlist, SENCOTEN_WORDLIST);
-    assert.isEmpty(testCallbacks.messages);
+    assert.isEmpty(callbacks.messages);
   });
 
   it('should NOT read word lists in UTF-16 big-endian (with BOM)', function () {
@@ -106,22 +105,22 @@ describe('parsing a word list', function () {
 
     assert.deepEqual(repeatedWords, expected);
 
-    assert.lengthOf(testCallbacks.messages, 4);
+    assert.lengthOf(callbacks.messages, 4);
     // hello has been seen multiple times:
-    assert.isTrue(testCallbacks.hasMessage(ModelCompilerMessages.HINT_DuplicateWordInSameFile));
+    assert.isTrue(callbacks.hasMessage(ModelCompilerMessages.HINT_DuplicateWordInSameFile));
     // helló and hello + U+0301 have both been seen:
-    assert.isTrue(testCallbacks.hasMessage(ModelCompilerMessages.HINT_MixedNormalizationForms));
+    assert.isTrue(callbacks.hasMessage(ModelCompilerMessages.HINT_MixedNormalizationForms));
 
     // Let's parse another file:
 
-    testCallbacks.clear();
+    callbacks.clear();
     // Now, parse a DIFFERENT file, but with an NFD entry.
     parseWordListFromContents(repeatedWords, "hello\u0301\t5\n");
-    assert.lengthOf(testCallbacks.messages, 1);
+    assert.lengthOf(callbacks.messages, 1);
     // hello + U+0301 (NFD) has been seen, but...
-    assert.isTrue(testCallbacks.hasMessage(ModelCompilerMessages.HINT_MixedNormalizationForms));
+    assert.isTrue(callbacks.hasMessage(ModelCompilerMessages.HINT_MixedNormalizationForms));
     // BUT! We have not seen a duplicate **within the same file**
-    assert.isFalse(testCallbacks.hasMessage(ModelCompilerMessages.HINT_DuplicateWordInSameFile));
+    assert.isFalse(callbacks.hasMessage(ModelCompilerMessages.HINT_DuplicateWordInSameFile));
 
     assert.deepEqual(repeatedWords, {
       hello: expected['hello'],
diff --git a/developer/src/kmc-model/test/punctuation.tests.ts b/developer/src/kmc-model/test/punctuation.tests.ts
index c3679f08d9..e0f1d661b4 100644
--- a/developer/src/kmc-model/test/punctuation.tests.ts
+++ b/developer/src/kmc-model/test/punctuation.tests.ts
@@ -6,12 +6,13 @@ import { makePathToFixture, compileModelSourceCode } from './helpers/index.js';
 import { TestCompilerCallbacks } from '@keymanapp/developer-test-helpers';
 
 describe('LexicalModelCompiler', function () {
+  const callbacks = new TestCompilerCallbacks(this);
+
   describe('specifying punctuation', function () {
     const MODEL_ID = 'example.qaa.trivial';
     const PATH = makePathToFixture(MODEL_ID);
 
     it('should compile punctuation into the generated code', async function () {
-      const callbacks = new TestCompilerCallbacks();
 
       const compiler = new LexicalModelCompiler();
       assert.isTrue(await compiler.init(callbacks, null));
diff --git a/developer/src/kmc-package/package.json b/developer/src/kmc-package/package.json
index edfba42073..e441b5d57b 100644
--- a/developer/src/kmc-package/package.json
+++ b/developer/src/kmc-package/package.json
@@ -36,8 +36,6 @@
   },
   "devDependencies": {
     "@keymanapp/developer-test-helpers": "*",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "chalk": "^2.4.2",
     "typescript": "^5.4.5"
diff --git a/developer/src/kmc-package/test/messages.tests.ts b/developer/src/kmc-package/test/messages.tests.ts
index 21f1e0e4a2..934226e024 100644
--- a/developer/src/kmc-package/test/messages.tests.ts
+++ b/developer/src/kmc-package/test/messages.tests.ts
@@ -10,15 +10,10 @@ import { makePathToFixture } from './helpers/index.js';
 import { KmpCompiler } from '../src/compiler/kmp-compiler.js';
 import { CompilerErrorNamespace, CompilerOptions } from '@keymanapp/developer-utils';
 
-const callbacks = new TestCompilerCallbacks();
 
 describe('PackageCompilerMessages', function () {
 
-  this.afterEach(function() {
-    if(this.currentTest.isFailed()) {
-      callbacks.printMessages();
-    }
-  });
+  const callbacks = new TestCompilerCallbacks(this);
 
   it('should have a valid PackageCompilerMessages object', function() {
     return verifyCompilerMessagesObject(PackageCompilerMessages, CompilerErrorNamespace.PackageCompiler);
diff --git a/developer/src/kmc-package/test/package-compiler.tests.ts b/developer/src/kmc-package/test/package-compiler.tests.ts
index 9dcad78054..77fbf75cdb 100644
--- a/developer/src/kmc-package/test/package-compiler.tests.ts
+++ b/developer/src/kmc-package/test/package-compiler.tests.ts
@@ -21,22 +21,14 @@ describe('KmpCompiler', function () {
     'example.qaa.sencoten',
     'withfolders.qaa.sencoten',
   ];
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
   let kmpCompiler: KmpCompiler = null;
 
   this.beforeAll(async function() {
-    callbacks.clear();
     kmpCompiler = new KmpCompiler();
     assert.isTrue(await kmpCompiler.init(callbacks, null));
   });
 
-  this.afterEach(function() {
-    if(this.currentTest?.isFailed()) {
-      callbacks.printMessages();
-    }
-    callbacks.clear();
-  });
-
   for (const modelID of MODELS) {
     const kpsPath = modelID.includes('withfolders') ?
       makePathToFixture(modelID, 'source', `${modelID}.model.kps`) : makePathToFixture(modelID, `${modelID}.model.kps`);
diff --git a/developer/src/kmc-package/test/versioning.tests.ts b/developer/src/kmc-package/test/versioning.tests.ts
index adcba30019..91ec523e65 100644
--- a/developer/src/kmc-package/test/versioning.tests.ts
+++ b/developer/src/kmc-package/test/versioning.tests.ts
@@ -11,6 +11,7 @@ import { makePathToFixture } from './helpers/index.js';
 // test results documented below.
 
 describe('package versioning', function () {
+  const callbacks = new TestCompilerCallbacks(this);
 
   const cases: [string,string][] = [
     ['test-single-version-1-package', 'test1.kps'],
@@ -33,7 +34,6 @@ describe('package versioning', function () {
 
   for(const [ caseTitle, filename ] of cases) {
     it(caseTitle, async function () {
-      const callbacks = new TestCompilerCallbacks();
       const kmpCompiler = new KmpCompiler();
       assert.isTrue(await kmpCompiler.init(callbacks, null));
 
diff --git a/developer/src/kmc-package/test/windows-package-installer-compiler.tests.ts b/developer/src/kmc-package/test/windows-package-installer-compiler.tests.ts
index f61b65d8aa..c4843942a7 100644
--- a/developer/src/kmc-package/test/windows-package-installer-compiler.tests.ts
+++ b/developer/src/kmc-package/test/windows-package-installer-compiler.tests.ts
@@ -9,6 +9,8 @@ import { makePathToFixture } from './helpers/index.js';
 import { WindowsPackageInstallerCompiler, WindowsPackageInstallerSources } from '../src/compiler/windows-package-installer-compiler.js';
 
 describe('WindowsPackageInstallerCompiler', function () {
+  const callbacks = new TestCompilerCallbacks(this);
+
   it(`should build an SFX archive`, async function () {
     this.timeout(10000); // this test can take a little while to run
 
@@ -22,7 +24,6 @@ describe('WindowsPackageInstallerCompiler', function () {
       appName: 'Testing',
     };
 
-    const callbacks = new TestCompilerCallbacks();
     const compiler = new WindowsPackageInstallerCompiler();
     assert.isTrue(await compiler.init(callbacks, {sources}));
 
@@ -44,7 +45,7 @@ describe('WindowsPackageInstallerCompiler', function () {
     const zipBuffer = sfxBuffer.slice(setupExeSize);
 
     // Verify setup.exe sfx loader
-    const setupExeFixture = fs.readFileSync(sources.setupExeFilename);
+    const setupExeFixture = fs.readFileSync(sources.setupExeFilename) as Uint8Array;
     assert.deepEqual(setupExe, setupExeFixture);
 
     // Load the zip from the buffer
@@ -68,7 +69,7 @@ khmer_angkor.kmp
     assert.equal(setupInf.trim(), setupInfFixture.trim());
 
     const verifyFile = async (filename: string) => {
-      const fixture = fs.readFileSync(filename);
+      const fixture = fs.readFileSync(filename) as Uint8Array;
       const file = await zipFile.file(path.basename(filename)).async('uint8array');
       assert.deepEqual(file, fixture, `File in zip '${filename}' did not match fixture`);
     };
diff --git a/developer/src/kmc/package.json b/developer/src/kmc/package.json
index 39d839bc84..4f15f5e98c 100644
--- a/developer/src/kmc/package.json
+++ b/developer/src/kmc/package.json
@@ -53,8 +53,6 @@
   ],
   "devDependencies": {
     "@sentry/cli": "^2.31.0",
-    "@types/mocha": "^5.2.7",
-    "@types/node": "^20.4.1",
     "c8": "^7.12.0",
     "esbuild": "^0.25.0",
     "typescript": "^5.4.5"
diff --git a/developer/src/server/package.json b/developer/src/server/package.json
index 37192ca6f3..ee58b4d649 100644
--- a/developer/src/server/package.json
+++ b/developer/src/server/package.json
@@ -29,9 +29,7 @@
     "@keymanapp/keyman-version": "*",
     "@keymanapp/resources-gosh": "*",
     "@types/express": "^4.17.13",
-    "@types/mocha": "^9.1.0",
     "@types/multer": "^1.4.12",
-    "@types/node": "^20.4.1",
     "@types/ws": "^8.2.2",
     "copyfiles": "^2.4.1",
     "node-gyp": "^10.2.0",
diff --git a/package-lock.json b/package-lock.json
index 61a304996b..ca632dbea4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -47,6 +47,7 @@
         "@microsoft/api-documenter": "^7.28.0",
         "@microsoft/api-extractor": "^7.47.3",
         "@types/chai": "^4.3.14",
+        "@types/mocha": "^10.0.10",
         "@types/node": "^20.4.1",
         "@typescript-eslint/eslint-plugin": "^7.13.1",
         "@web/dev-server-esbuild": "^1.0.2",
@@ -149,8 +150,6 @@
         "restructure": "3.0.1"
       },
       "devDependencies": {
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "ajv": "^8.12.0",
         "ajv-cli": "^5.0.0",
         "ajv-formats": "^2.1.1",
@@ -160,11 +159,6 @@
         "typescript": "^5.4.5"
       }
     },
-    "common/web/types/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "dev": true,
-      "license": "MIT"
-    },
     "common/web/types/node_modules/ansi-styles": {
       "version": "3.2.1",
       "dev": true,
@@ -285,8 +279,6 @@
       },
       "devDependencies": {
         "@sentry/cli": "^2.31.0",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "esbuild": "^0.25.0",
         "typescript": "^5.4.5"
@@ -302,19 +294,11 @@
       },
       "devDependencies": {
         "@keymanapp/resources-gosh": "*",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "chalk": "^2.4.2",
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-analyze/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.7.tgz",
-      "integrity": "sha512-NYrtPht0wGzhwe9+/idPaBB+TqkY9AhTvOLMkThm0IoEfLaiVQZwBwyJ5puCkO3AUCWrmcoePjp2mbFocKy4SQ==",
-      "dev": true
-    },
     "developer/src/kmc-analyze/node_modules/ansi-styles": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
@@ -581,19 +565,11 @@
         "@keymanapp/langtags": "*"
       },
       "devDependencies": {
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "chalk": "^2.4.2",
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-keyboard-info/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.7.tgz",
-      "integrity": "sha512-NYrtPht0wGzhwe9+/idPaBB+TqkY9AhTvOLMkThm0IoEfLaiVQZwBwyJ5puCkO3AUCWrmcoePjp2mbFocKy4SQ==",
-      "dev": true
-    },
     "developer/src/kmc-keyboard-info/node_modules/ansi-styles": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
@@ -666,8 +642,6 @@
       },
       "devDependencies": {
         "@keymanapp/developer-test-helpers": "*",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "@types/semver": "^7.3.12",
         "@types/sinon": "^10.0.13",
         "@types/sinon-chai": "^3.2.9",
@@ -677,12 +651,6 @@
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-kmn/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.7.tgz",
-      "integrity": "sha512-NYrtPht0wGzhwe9+/idPaBB+TqkY9AhTvOLMkThm0IoEfLaiVQZwBwyJ5puCkO3AUCWrmcoePjp2mbFocKy4SQ==",
-      "dev": true
-    },
     "developer/src/kmc-kmn/node_modules/ansi-styles": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
@@ -759,8 +727,6 @@
         "@keymanapp/developer-test-helpers": "*",
         "@keymanapp/resources-gosh": "*",
         "@types/common-tags": "^1.8.4",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "@types/semver": "^7.3.12",
         "abnf": "^4.3.1",
         "c8": "^7.12.0",
@@ -770,12 +736,6 @@
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-ldml/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.7.tgz",
-      "integrity": "sha512-NYrtPht0wGzhwe9+/idPaBB+TqkY9AhTvOLMkThm0IoEfLaiVQZwBwyJ5puCkO3AUCWrmcoePjp2mbFocKy4SQ==",
-      "dev": true
-    },
     "developer/src/kmc-ldml/node_modules/ansi-styles": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
@@ -849,8 +809,6 @@
       "devDependencies": {
         "@keymanapp/developer-test-helpers": "*",
         "@keymanapp/models-templates": "*",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "chalk": "^2.4.2",
         "esbuild": "^0.25.0"
@@ -864,18 +822,11 @@
         "@keymanapp/developer-utils": "*"
       },
       "devDependencies": {
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "chalk": "^2.4.2",
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-model-info/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "dev": true,
-      "license": "MIT"
-    },
     "developer/src/kmc-model-info/node_modules/ansi-styles": {
       "version": "3.2.1",
       "dev": true,
@@ -932,11 +883,6 @@
         "node": ">=4"
       }
     },
-    "developer/src/kmc-model/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "dev": true,
-      "license": "MIT"
-    },
     "developer/src/kmc-model/node_modules/ansi-styles": {
       "version": "3.2.1",
       "dev": true,
@@ -1004,18 +950,11 @@
       },
       "devDependencies": {
         "@keymanapp/developer-test-helpers": "*",
-        "@types/mocha": "^5.2.7",
-        "@types/node": "^20.4.1",
         "c8": "^7.12.0",
         "chalk": "^2.4.2",
         "typescript": "^5.4.5"
       }
     },
-    "developer/src/kmc-package/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "dev": true,
-      "license": "MIT"
-    },
     "developer/src/kmc-package/node_modules/ansi-styles": {
       "version": "3.2.1",
       "dev": true,
@@ -1072,11 +1011,6 @@
         "node": ">=4"
       }
     },
-    "developer/src/kmc/node_modules/@types/mocha": {
-      "version": "5.2.7",
-      "dev": true,
-      "license": "MIT"
-    },
     "developer/src/kmc/node_modules/ansi-styles": {
       "version": "3.2.1",
       "license": "MIT",
@@ -1162,9 +1096,7 @@
         "@keymanapp/keyman-version": "*",
         "@keymanapp/resources-gosh": "*",
         "@types/express": "^4.17.13",
-        "@types/mocha": "^9.1.0",
         "@types/multer": "^1.4.12",
-        "@types/node": "^20.4.1",
         "@types/ws": "^8.2.2",
         "copyfiles": "^2.4.1",
         "node-gyp": "^10.2.0",
@@ -1175,11 +1107,6 @@
         "node-hide-console-window": "^2.2.0"
       }
     },
-    "developer/src/server/node_modules/@types/mocha": {
-      "version": "9.1.1",
-      "dev": true,
-      "license": "MIT"
-    },
     "developer/src/server/node_modules/@types/multer": {
       "version": "1.4.12",
       "resolved": "https://registry.npmjs.org/@types/multer/-/multer-1.4.12.tgz",
@@ -3480,7 +3407,9 @@
       "license": "MIT"
     },
     "node_modules/@types/mocha": {
-      "version": "7.0.2",
+      "version": "10.0.10",
+      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-10.0.10.tgz",
+      "integrity": "sha512-xPyYSz1cMPnJQhl0CLMH68j3gprKZaTjG3s5Vi+fDgx+uhG9NOXwbVt52eFS8ECyXhyKcjDLCBEqBExKuiZb7Q==",
       "dev": true,
       "license": "MIT"
     },
@@ -4679,6 +4608,15 @@
       "integrity": "sha512-klpgFSWLW1ZEs8svjfb7g4qWY0YS5imI82dTg+QahUvJ8YqAY0P10Uk8tTyh9ZGuYEZEMaeJYCF5BFuX552hsw==",
       "license": "MIT"
     },
+    "node_modules/arg": {
+      "version": "4.1.3",
+      "resolved": "https://registry.npmjs.org/arg/-/arg-4.1.3.tgz",
+      "integrity": "sha512-58S9QDqG0Xx27YwPSt9fJxivjYl432YCwfDMfZ+71RAqUrZef7LrKQZ3LHLOwCS4FLNBplP533Zx895SeOCHvA==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true
+    },
     "node_modules/argparse": {
       "version": "2.0.1",
       "dev": true,
@@ -5842,6 +5780,15 @@
       "version": "1.0.3",
       "license": "MIT"
     },
+    "node_modules/create-require": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/create-require/-/create-require-1.1.1.tgz",
+      "integrity": "sha512-dcKFX3jn0MpIaXjisoRvexIJVEKzaq7z2rZKxf+MSr9TkdmHmsU4m2lcLojrj/FHl8mk5VxMmYA+ftRkP/3oKQ==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true
+    },
     "node_modules/cross-spawn": {
       "version": "7.0.6",
       "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-7.0.6.tgz",
@@ -9846,6 +9793,15 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/make-error": {
+      "version": "1.3.6",
+      "resolved": "https://registry.npmjs.org/make-error/-/make-error-1.3.6.tgz",
+      "integrity": "sha512-s8UhlNe7vPKomQhC1qFelMokr/Sc3AgNbso3n74mVPA5LTZwkB9NlXf4XPamLxJE8h0gh73rM94xvwRT2CVInw==",
+      "dev": true,
+      "license": "ISC",
+      "optional": true,
+      "peer": true
+    },
     "node_modules/make-fetch-happen": {
       "version": "13.0.1",
       "resolved": "https://registry.npmjs.org/make-fetch-happen/-/make-fetch-happen-13.0.1.tgz",
@@ -12939,6 +12895,47 @@
         "typescript": ">=4.2.0"
       }
     },
+    "node_modules/ts-node": {
+      "version": "9.1.1",
+      "resolved": "https://registry.npmjs.org/ts-node/-/ts-node-9.1.1.tgz",
+      "integrity": "sha512-hPlt7ZACERQGf03M253ytLY3dHbGNGrAq9qIHWUY9XHYl1z7wYngSr3OQ5xmui8o2AaxsONxIzjafLUiWBo1Fg==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "dependencies": {
+        "arg": "^4.1.0",
+        "create-require": "^1.1.0",
+        "diff": "^4.0.1",
+        "make-error": "^1.1.1",
+        "source-map-support": "^0.5.17",
+        "yn": "3.1.1"
+      },
+      "bin": {
+        "ts-node": "dist/bin.js",
+        "ts-node-script": "dist/bin-script.js",
+        "ts-node-transpile-only": "dist/bin-transpile.js",
+        "ts-script": "dist/bin-script-deprecated.js"
+      },
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "peerDependencies": {
+        "typescript": ">=2.7"
+      }
+    },
+    "node_modules/ts-node/node_modules/diff": {
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-4.0.4.tgz",
+      "integrity": "sha512-X07nttJQkwkfKfvTPG/KSnE2OMdcUCao6+eXF3wmnIQRn2aPAHH3VxDbDOdegkd6JbPsXqShpvEOHfAT+nCNwQ==",
+      "dev": true,
+      "license": "BSD-3-Clause",
+      "optional": true,
+      "peer": true,
+      "engines": {
+        "node": ">=0.3.1"
+      }
+    },
     "node_modules/tsc-watch": {
       "version": "4.6.2",
       "dev": true,
@@ -13779,6 +13776,18 @@
         "node": ">= 4.0.0"
       }
     },
+    "node_modules/yn": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/yn/-/yn-3.1.1.tgz",
+      "integrity": "sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/yocto-queue": {
       "version": "0.1.0",
       "dev": true,
@@ -14097,7 +14106,6 @@
       "devDependencies": {
         "@keymanapp/common-types": "*",
         "@keymanapp/web-utils": "*",
-        "@types/mocha": "^7.0.2",
         "c8": "^7.12.0",
         "typescript": "^5.4.5"
       }
@@ -14115,7 +14123,6 @@
       "devDependencies": {
         "@keymanapp/common-types": "*",
         "@keymanapp/resources-gosh": "*",
-        "@types/mocha": "^7.0.2",
         "c8": "^7.12.0",
         "typescript": "^5.4.5"
       }
diff --git a/package.json b/package.json
index 7f033959d8..8bad452796 100644
--- a/package.json
+++ b/package.json
@@ -5,6 +5,7 @@
     "@microsoft/api-documenter": "^7.28.0",
     "@microsoft/api-extractor": "^7.47.3",
     "@types/chai": "^4.3.14",
+    "@types/mocha": "^10.0.10",
     "@types/node": "^20.4.1",
     "@typescript-eslint/eslint-plugin": "^7.13.1",
     "@web/dev-server-esbuild": "^1.0.2",
diff --git a/web/src/engine/predictive-text/templates/package.json b/web/src/engine/predictive-text/templates/package.json
index cbe3fb8747..fc1deedbfb 100644
--- a/web/src/engine/predictive-text/templates/package.json
+++ b/web/src/engine/predictive-text/templates/package.json
@@ -53,7 +53,6 @@
   "devDependencies": {
     "@keymanapp/common-types": "*",
     "@keymanapp/web-utils": "*",
-    "@types/mocha": "^7.0.2",
     "c8": "^7.12.0",
     "typescript": "^5.4.5"
   },
diff --git a/web/src/engine/predictive-text/wordbreakers/package.json b/web/src/engine/predictive-text/wordbreakers/package.json
index 0f73f19f69..5ebe40654b 100644
--- a/web/src/engine/predictive-text/wordbreakers/package.json
+++ b/web/src/engine/predictive-text/wordbreakers/package.json
@@ -56,7 +56,6 @@
   "devDependencies": {
     "@keymanapp/common-types": "*",
     "@keymanapp/resources-gosh": "*",
-    "@types/mocha": "^7.0.2",
     "c8": "^7.12.0",
     "typescript": "^5.4.5"
   },
diff --git a/web/src/test/auto/headless/engine/main/headless/languageProcessor.tests.js b/web/src/test/auto/headless/engine/main/headless/languageProcessor.tests.js
index 6d866ef8ed..e5b8856016 100644
--- a/web/src/test/auto/headless/engine/main/headless/languageProcessor.tests.js
+++ b/web/src/test/auto/headless/engine/main/headless/languageProcessor.tests.js
@@ -22,11 +22,10 @@ global.keyman = {}; // So that keyboard-based checks against the global `keyman`
 // Test the KeyboardProcessor interface.
 describe('LanguageProcessor', function() {
   let languageProcessor;
-  const callbacks = new TestCompilerCallbacks();
+  const callbacks = new TestCompilerCallbacks(this);
 
   beforeEach(function() {
     languageProcessor = new LanguageProcessor(LMWorker, new TranscriptionCache());
-    callbacks.clear();
   });
 
   afterEach(function() {