Convert library to ES modules

[willdurand]

Fixes #1078

---

This PR converts the library to ES modules and this is similar to mozilla/web-ext#2405.

Summary

• Convert the entire library to ES modules
• No more webpack, it is using babel like web-ext
• ESM library that exposes signAddon and signAddonAndExit with the option of dynamically importing the library in commonjs (await import())

Public API

I verified the public API by npm pack'ing this work and npm i /path/to/sign-addon-4.1.0.tgz in a temporary directory. Then I created two scripts, one for commonjs and one for esmodules. The APIs are the same except that commonjs has a default, which I think is expected.

❯ cat test.js
  (async () => {
      let signAddon = await import('sign-addon');

      console.log(signAddon)
  })();

❯ node test.js
[Module: null prototype] {
  default: [Module: null prototype] {
    signAddon: [AsyncFunction: signAddon],
    signAddonAndExit: [AsyncFunction: signAddonAndExit]
  },
  signAddon: [AsyncFunction: signAddon],
  signAddonAndExit: [AsyncFunction: signAddonAndExit]
}

and:

❯ cat test.mjs
  import signAddon from 'sign-addon';

  console.log(signAddon)

❯ node test.mjs
[Module: null prototype] {
  signAddon: [AsyncFunction: signAddon],
  signAddonAndExit: [AsyncFunction: signAddonAndExit]
}

[willdurand]

I have no idea what has changed here tbh :/

[rpl]

not sure what made tsc to start to complain, but it seems that it may be able to stop complaining with a bit of help (but I haven't used typescript as much as flowtype and so I don't exclude I may have tricked tsc to stop complaining in an incorrect way)

The following tweaked version passed npm run typecheck (and also npm run lint and npm run test) for me locally and so may consider if we prefer using this approach as an alternative to the @ts-ignore (not a big deal though):

diff --git a/tests/index.spec.js b/tests/index.spec.js
index 1500c48..a673759 100644
--- a/tests/index.spec.js
+++ b/tests/index.spec.js
@@ -69,17 +69,20 @@ describe(fileURLToPath(import.meta.url), () => {
         // @ts-ignore
         this.debug = jest.fn();
 
-        // @ts-ignore - TypeScript refuses to change the type of the mock...
-        signingCall = jest.fn().mockImplementation(
-          // eslint-disable-next-line no-unused-vars
-          (params) =>
-            new Promise((resolve) => {
-              if (options.errorToThrow) {
-                throw options.errorToThrow;
-              }
-              resolve(options.result);
-            }),
-        );
+        /** @type {(params: SignParams) => Promise<SignResult>} */
+        // eslint-disable-next-line no-unused-vars
+        const mockedSigningCall = (params) =>
+          new Promise((resolve) => {
+            if (options.errorToThrow) {
+              throw options.errorToThrow;
+            }
+            resolve(options.result);
+          });
+
+        /**
+         * @type {jest.Mock<(params: SignParams) => Promise<SignResult>>}
+         */
+        signingCall = jest.fn(this.sign).mockImplementation(mockedSigningCall);

[rpl]

@willdurand this looks great, follows a couple of comments, but they seems mainly nice to have and so I'm approving this version along with submitting those.

I'm happy to give this another look if we decide to integrate some more tweaks from the review comments below.

[rpl]

not sure what made tsc to start to complain, but it seems that it may be able to stop complaining with a bit of help (but I haven't used typescript as much as flowtype and so I don't exclude I may have tricked tsc to stop complaining in an incorrect way)

The following tweaked version passed npm run typecheck (and also npm run lint and npm run test) for me locally and so may consider if we prefer using this approach as an alternative to the @ts-ignore (not a big deal though):

diff --git a/tests/index.spec.js b/tests/index.spec.js
index 1500c48..a673759 100644
--- a/tests/index.spec.js
+++ b/tests/index.spec.js
@@ -69,17 +69,20 @@ describe(fileURLToPath(import.meta.url), () => {
         // @ts-ignore
         this.debug = jest.fn();
 
-        // @ts-ignore - TypeScript refuses to change the type of the mock...
-        signingCall = jest.fn().mockImplementation(
-          // eslint-disable-next-line no-unused-vars
-          (params) =>
-            new Promise((resolve) => {
-              if (options.errorToThrow) {
-                throw options.errorToThrow;
-              }
-              resolve(options.result);
-            }),
-        );
+        /** @type {(params: SignParams) => Promise<SignResult>} */
+        // eslint-disable-next-line no-unused-vars
+        const mockedSigningCall = (params) =>
+          new Promise((resolve) => {
+            if (options.errorToThrow) {
+              throw options.errorToThrow;
+            }
+            resolve(options.result);
+          });
+
+        /**
+         * @type {jest.Mock<(params: SignParams) => Promise<SignResult>>}
+         */
+        signingCall = jest.fn(this.sign).mockImplementation(mockedSigningCall);