Improve error messages when packages are not installed (#764).

README.md

@@ -281,8 +281,8 @@ Please note that, due to the complex interactions when forming ligations, cherry
 
 To build Iosevka you should:
 
-1. Ensure that [`nodejs`](http://nodejs.org) (≥ 12.16.0) and [`ttfautohint`](http://www.freetype.org/ttfautohint/) are present.
-2. Install necessary libs by `npm install`. If you’ve installed them, upgrade to the latest.
+1. Ensure that [`nodejs`](http://nodejs.org) (≥ 12.16.0) and [`ttfautohint`](http://www.freetype.org/ttfautohint/) are present, and accessible from `PATH`.
+2. Run `npm install`. This command will install **all** the NPM dependenceis, and will also validate whether external dependencies are present.
 3. `npm run build -- contents::iosevka`.
 
 You will find TTFs, as well as WOFF(2) web fonts and one Webfont CSS in the `dist/` directory.

package.json

@@ -3,10 +3,9 @@
   "version": "4.0.0",
   "main": "./font-src/index.js",
   "scripts": {
-    "build": "verda -f verdafile.js",
+    "build": "node utility/ensure-verda-exists && verda -f verdafile.js",
     "bump-ver": "node utility/update-package-json-version/index",
-    "clean": "verda -f verdafile.js clean",
-    "install": "node utility/check-env"
+    "clean": "node utility/ensure-verda-exists && verda -f verdafile.js clean"
   },
   "dependencies": {
     "@iarna/toml": "^2.2.5",
@@ -23,7 +22,7 @@
     "stylus": "^0.54.8",
     "toposort": "^2.0.2",
     "typo-geom": "^0.11.0",
-    "verda": "^1.1.2",
+    "verda": "^1.2.0",
     "wawoff2": "^1.0.2",
     "which": "^2.0.2"
   },

utility/check-env.js

@@ -1,19 +0,0 @@
-"use strict";
-
-const which = require("which");
-const FgRed = "\x1b[31m";
-const FgGreen = "\x1b[32m";
-const FgYellow = "\x1b[33m";
-const Reset = "\x1b[0m";
-
-console.log("Checking External Dependencies");
-check("ttfautohint");
-
-function check(util) {
-	try {
-		which.sync(util);
-		console.error(FgGreen + ` * External dependency <${util}> is present.` + Reset);
-	} catch (e) {
-		console.error(FgRed + ` * External dependency <${util}> is not found.` + Reset);
-	}
-}

utility/ensure-verda-exists.js

@@ -0,0 +1,23 @@
+"use strict";
+
+const FgRed = "\x1b[31m";
+const FgYellow = "\x1b[33m";
+const Reset = "\x1b[0m";
+
+const os = require("os");
+const shellWord = os.platform() === "win32" ? "command prompt" : "shell";
+
+// Check packages are present
+try {
+	require("verda/package.json");
+	require("semver/package.json");
+	require("which/package.json");
+	require("@iarna/toml/package.json");
+} catch (e) {
+	console.error(`${FgRed}It looks like you forgot to run "npm install" before building.${Reset}`);
+	console.error(`"npm install" sets up dependencies required to build the fonts.`);
+	console.error(`Run the following command in your ${shellWord} and retry:`);
+	console.error(`    ${FgYellow}npm install${Reset}`);
+	console.error();
+	process.exit(1);
+}

verdafile.js

@@ -2,26 +2,27 @@
 
 const fs = require("fs");
 const build = require("verda").create();
+const which = require("which");
+const Path = require("path");
+const toml = require("@iarna/toml");
+
+///////////////////////////////////////////////////////////
+
 const { task, file, oracle, computed, phony } = build.ruleTypes;
 const { de, fu, sfu, ofu } = build.rules;
-const { run, node, cd, cp, rm, mv, fail, echo } = build.actions;
+const { run, node, cd, cp, rm, mv, fail, echo, silently } = build.actions;
 const { FileList } = build.predefinedFuncs;
-const which = require("which");
 
 module.exports = build;
 
 ///////////////////////////////////////////////////////////
 
-const Path = require("path");
-const toml = require("@iarna/toml");
-
 const BUILD = ".build";
 const DIST = "dist";
 const SNAPSHOT_TMP = ".build/snapshot";
 const DIST_SUPER_TTC = "dist/.super-ttc";
 const ARCHIVE_DIR = "release-archives";
 
-const TTX = "ttx";
 const PATEL_C = ["node", "./node_modules/patel/bin/patel-c"];
 const TTCIZE = ["node", "node_modules/otb-ttc-bundle/bin/otb-ttc-bundle"];
 const webfontFormats = [
@@ -52,6 +53,14 @@ const Version = oracle(`oracle:version`, async target => {
 	return package_json.version;
 });
 
+const CheckTtfAutoHintExists = oracle(`oracle:check-ttfautohint-exists`, async target => {
+	try {
+		return await which("ttfautohint");
+	} catch (e) {
+		fail("External dependency <ttfautohint>, needed for building hinted font, does not exist.");
+	}
+});
+
 ///////////////////////////////////////////////////////////
 //////                    Plans                      //////
 ///////////////////////////////////////////////////////////
@@ -309,9 +318,9 @@ const DistUnhintedTTF = file.make(
 const DistHintedTTF = file.make(
 	(gr, fn) => `${DIST}/${gr}/ttf/${fn}.ttf`,
 	async (target, path, gr, f) => {
-		const [{ hintParams }] = await target.need(FontInfoOf(f));
+		const [{ hintParams }, hint] = await target.need(FontInfoOf(f), CheckTtfAutoHintExists);
 		const [from] = await target.need(BuildTTF(gr, f), de`${path.dir}`);
-		await run("ttfautohint", hintParams, from.full, path.full);
+		await silently.run(hint, hintParams, from.full, path.full);
 	}
 );
 const DistWoff2 = file.make(