diff --git a/test/e2e/tsdx-build-default.test.js b/test/e2e/tsdx-build-default.test.ts
similarity index 95%
rename from test/e2e/tsdx-build-default.test.js
rename to test/e2e/tsdx-build-default.test.ts
index 5a1c0f52..95814119 100644
--- a/test/e2e/tsdx-build-default.test.js
+++ b/test/e2e/tsdx-build-default.test.ts
@@ -1,6 +1,7 @@
-const shell = require('shelljs');
-const util = require('../utils/fixture');
-const { execWithCache } = require('../utils/shell');
+import * as shell from 'shelljs';
+
+import * as util from '../utils/fixture';
+import { execWithCache } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/e2e/tsdx-build-invalid.test.js b/test/e2e/tsdx-build-invalid.test.ts
similarity index 89%
rename from test/e2e/tsdx-build-invalid.test.js
rename to test/e2e/tsdx-build-invalid.test.ts
index ccc3a937..3bf8c80b 100644
--- a/test/e2e/tsdx-build-invalid.test.js
+++ b/test/e2e/tsdx-build-invalid.test.ts
@@ -1,6 +1,7 @@
-const shell = require('shelljs');
-const util = require('../utils/fixture');
-const { execWithCache } = require('../utils/shell');
+import * as shell from 'shelljs';
+
+import * as util from '../utils/fixture';
+import { execWithCache } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/e2e/tsdx-build-withTsconfig.test.js b/test/e2e/tsdx-build-withTsconfig.test.ts
similarity index 94%
rename from test/e2e/tsdx-build-withTsconfig.test.js
rename to test/e2e/tsdx-build-withTsconfig.test.ts
index 14aca52d..9474104d 100644
--- a/test/e2e/tsdx-build-withTsconfig.test.js
+++ b/test/e2e/tsdx-build-withTsconfig.test.ts
@@ -1,6 +1,7 @@
-const shell = require('shelljs');
-const util = require('../utils/fixture');
-const { execWithCache } = require('../utils/shell');
+import * as shell from 'shelljs';
+
+import * as util from '../utils/fixture';
+import { execWithCache } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/e2e/tsdx-lint.test.js b/test/e2e/tsdx-lint.test.ts
similarity index 96%
rename from test/e2e/tsdx-lint.test.js
rename to test/e2e/tsdx-lint.test.ts
index 68831a49..f04327e3 100644
--- a/test/e2e/tsdx-lint.test.js
+++ b/test/e2e/tsdx-lint.test.ts
@@ -1,6 +1,6 @@
-const shell = require('shelljs');
+import * as shell from 'shelljs';
 
-const util = require('../utils/fixture');
+import * as util from '../utils/fixture';
 
 shell.config.silent = true;
 
diff --git a/test/integration/tsdx-build-options.test.js b/test/integration/tsdx-build-options.test.ts
similarity index 93%
rename from test/integration/tsdx-build-options.test.js
rename to test/integration/tsdx-build-options.test.ts
index db002bf6..d6c28644 100644
--- a/test/integration/tsdx-build-options.test.js
+++ b/test/integration/tsdx-build-options.test.ts
@@ -1,7 +1,7 @@
-const shell = require('shelljs');
+import * as shell from 'shelljs';
 
-const util = require('../utils/fixture');
-const { execWithCache } = require('../utils/shell');
+import * as util from '../utils/fixture';
+import { execWithCache } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/integration/tsdx-build-withBabel.test.js b/test/integration/tsdx-build-withBabel.test.ts
similarity index 94%
rename from test/integration/tsdx-build-withBabel.test.js
rename to test/integration/tsdx-build-withBabel.test.ts
index cb2b3b59..26b03762 100644
--- a/test/integration/tsdx-build-withBabel.test.js
+++ b/test/integration/tsdx-build-withBabel.test.ts
@@ -1,7 +1,7 @@
-const shell = require('shelljs');
+import * as shell from 'shelljs';
 
-const util = require('../utils/fixture');
-const { execWithCache, grep } = require('../utils/shell');
+import * as util from '../utils/fixture';
+import { execWithCache, grep } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/integration/tsdx-build-withConfig.test.js b/test/integration/tsdx-build-withConfig.test.ts
similarity index 91%
rename from test/integration/tsdx-build-withConfig.test.js
rename to test/integration/tsdx-build-withConfig.test.ts
index fa4d9ee5..ecd6d886 100644
--- a/test/integration/tsdx-build-withConfig.test.js
+++ b/test/integration/tsdx-build-withConfig.test.ts
@@ -1,8 +1,8 @@
-const shell = require('shelljs');
-const fs = require('fs-extra');
+import * as fs from 'fs-extra';
+import * as shell from 'shelljs';
 
-const util = require('../utils/fixture');
-const { execWithCache } = require('../utils/shell');
+import * as util from '../utils/fixture';
+import { execWithCache } from '../utils/shell';
 
 shell.config.silent = false;
 
diff --git a/test/utils/fixture.js b/test/utils/fixture.js
deleted file mode 100644
index df4145df..00000000
--- a/test/utils/fixture.js
+++ /dev/null
@@ -1,28 +0,0 @@
-const shell = require('shelljs');
-const path = require('path');
-const rootDir = process.cwd();
-
-shell.config.silent = true;
-
-module.exports = {
-  setupStageWithFixture: (testDir, stageName, fixtureName) => {
-    const stagePath = path.join(rootDir, stageName);
-    shell.mkdir(stagePath);
-    shell.exec(
-      `cp -a ${rootDir}/test/${testDir}/fixtures/${fixtureName}/. ${stagePath}/`
-    );
-    shell.ln(
-      '-s',
-      path.join(rootDir, 'node_modules'),
-      path.join(stagePath, 'node_modules')
-    );
-    shell.cd(stagePath);
-  },
-
-  teardownStage: stageName => {
-    shell.cd(rootDir);
-    shell.rm('-rf', path.join(rootDir, stageName));
-  },
-
-  rootDir,
-};
diff --git a/test/utils/fixture.ts b/test/utils/fixture.ts
new file mode 100644
index 00000000..148b1e4c
--- /dev/null
+++ b/test/utils/fixture.ts
@@ -0,0 +1,29 @@
+import * as path from 'path';
+import * as shell from 'shelljs';
+
+export const rootDir = process.cwd();
+
+shell.config.silent = true;
+
+export function setupStageWithFixture(
+  testDir: string,
+  stageName: string,
+  fixtureName: string
+): void {
+  const stagePath = path.join(rootDir, stageName);
+  shell.mkdir(stagePath);
+  shell.exec(
+    `cp -a ${rootDir}/test/${testDir}/fixtures/${fixtureName}/. ${stagePath}/`
+  );
+  shell.ln(
+    '-s',
+    path.join(rootDir, 'node_modules'),
+    path.join(stagePath, 'node_modules')
+  );
+  shell.cd(stagePath);
+}
+
+export function teardownStage(stageName: string): void {
+  shell.cd(rootDir);
+  shell.rm('-rf', path.join(rootDir, stageName));
+}
diff --git a/test/utils/shell.js b/test/utils/shell.ts
similarity index 67%
rename from test/utils/shell.js
rename to test/utils/shell.ts
index c267ddc0..ee0b4b7a 100644
--- a/test/utils/shell.js
+++ b/test/utils/shell.ts
@@ -1,12 +1,15 @@
 // this file contains helper utils for working with shell.js functions
-const shell = require('shelljs');
+import * as shell from 'shelljs';
 
 shell.config.silent = true;
 
 // simple shell.exec "cache" that doesn't re-run the same command twice in a row
 let prevCommand = '';
-let prevCommandOutput = {};
-function execWithCache(command, { noCache = false } = {}) {
+let prevCommandOutput = {} as shell.ShellReturnValue;
+export function execWithCache(
+  command: string,
+  { noCache = false } = {}
+): shell.ShellReturnValue {
   // return the old output
   if (!noCache && prevCommand === command) return prevCommandOutput;
 
@@ -15,7 +18,7 @@ function execWithCache(command, { noCache = false } = {}) {
   // reset if command is not to be cached
   if (noCache) {
     prevCommand = '';
-    prevCommandOutput = {};
+    prevCommandOutput = {} as shell.ShellReturnValue;
   } else {
     prevCommand = command;
     prevCommandOutput = output;
@@ -24,19 +27,11 @@ function execWithCache(command, { noCache = false } = {}) {
   return output;
 }
 
-// shelljs.grep wrapper
-// @param {RegExp} pattern
-// @param {string} fileName
-// @returns {boolean} true if pattern has matches in file
-function grep(pattern, fileName) {
+// shell.js grep wrapper returns true if pattern has matches in file
+export function grep(pattern: RegExp, fileName: string[]): boolean {
   const output = shell.grep(pattern, fileName);
   // output.code is always 0 regardless of matched/unmatched patterns
   // so need to test output.stdout
   // https://github.com/jaredpalmer/tsdx/pull/525#discussion_r395571779
   return Boolean(output.stdout.match(pattern));
 }
-
-module.exports = {
-  execWithCache,
-  grep,
-};