tests/assert-install.sh: Always to enforce correct installation

Also in this change:

- now we call ln(1) in the "install" target without using the -r
  "relative" flag, as it isn't POSIX;
- add `+` as a prefix to the "assert-tests" command, so we tell sub-make
  calls to also run things in parallel.  In this case, the
  "make DESTDIR=... install" calls;
- use the implicit `index.js` entrypoint and do away completly with
  `package.json`;
- change from `import` to `require` as Node.js ESM modules don't support
  `$NODE_PATH`[0]: "NODE_PATH is not part of resolving import
  specifiers. Please use symlinks if this behavior is desired." 🤦;

The parallel sub-make behaviour isn't available in current specification
of make (POSIX issue 7) but is included in the upcoming[1] version 8:

> If a rule invokes a sub-make either via the MAKE macro or via a
> command line that begins with '+', the sub-make is the same
> implementation as the make that invoked the sub-make, and the −j
> option is passed to the sub-make via the MAKEFLAGS environment
> variable with the same maxjobs value and is not overridden by a
> maxjobs value from another source (even if it has the same value), the
> sub-make shall use the same token pool as its invoking make rather
> than create a new token pool.

[0]: https://nodejs.org/api/esm.html#no-node_path
[1]: https://www.opengroup.org/austin/restricted/202x-d3/202x_d3.pdf

1 files changed, 43 insertions, 0 deletions

diff --git a/src/utils.js b/src/utils.js
new file mode 100644
index 0000000..1877a58
--- /dev/null
+++ b/src/utils.js
@@ -0,0 +1,43 @@
+const eq = (a, b) => {
+	if (a === b) {
+		return true;
+	}
+
+	if (a === null || b === null) {
+		return false;
+	}
+
+	if (typeof a != "object" || typeof b != "object") {
+		return false;
+	}
+
+	if (Array.isArray(a) !== Array.isArray(b)) {
+		return false;
+	}
+
+	if (Object.keys(a).length !== Object.keys(b).length) {
+		return false;
+	}
+
+	for (const k in a) {
+		if (!b.hasOwnProperty(k)) {
+			return false;
+		}
+		if (!eq(a[k], b[k])) {
+			return false;
+		}
+	}
+	return true;
+};
+
+const keys = (ks, obj) =>
+	ks.reduce(
+		(ret, k) =>
+			obj.hasOwnProperty(k) ?  {...ret, [k]: obj[k]} : ret,
+		{},
+	);
+
+module.exports = {
+	eq,
+	keys,
+};