From a308072cd99cd97d7fff02c73fbf9d54ee4d61d3 Mon Sep 17 00:00:00 2001
From: Michael van Engelshoven <michael@van-engelshoven.de>
Date: Fri, 15 Sep 2023 08:57:41 +0200
Subject: [PATCH] added experimental support for symlinked modules

When linking external dependencies using `npm_link`, rollups commonjs
plugin does not process files in the symlinked directory correctly. To
support this, rollup need the `preserveSymlinks` setting to be true.

Since we cannot assess at the moment whether this setting will break
some other build, we put it behind an experimental flag. So you need to
set the environment varialbe `FAUCET_EXPERIMENTAL_SYMLINKS` to `"true"`
to enable preserving symlinks.
---
 lib/bundle/config.js                          |  9 +++-
 .../fixtures/external/cjs-module/index.js     |  3 ++
 test/unit/fixtures/src/import-symlinked.js    |  3 ++
 test/unit/test_bundling.js                    | 46 +++++++++++++++++++
 4 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 test/unit/fixtures/external/cjs-module/index.js
 create mode 100644 test/unit/fixtures/src/import-symlinked.js

diff --git a/lib/bundle/config.js b/lib/bundle/config.js
index 7e020fa..449c633 100644
--- a/lib/bundle/config.js
+++ b/lib/bundle/config.js
@@ -88,8 +88,13 @@ function generateConfig({ externals, format, exports, // eslint-disable-next-lin
 
 	plugins = plugins.concat([
 		nodeResolve({ extensions }),
-		commonjs({ include: "node_modules/**" })
+		commonjs({ include: /node_modules/ })
 	]);
+
+	if(process.env.FAUCET_EXPERIMENTAL_SYMLINKS === "true") {
+		cfg.preserveSymlinks = true;
+	}
+
 	if(compact) {
 		cfg.compact = true;
 		plugins = plugins.concat(determineCompacting(compact));
@@ -111,7 +116,7 @@ function generateConfig({ externals, format, exports, // eslint-disable-next-lin
 	}
 
 	// distinguish between (roughly) read and write settings
-	let read = ["external", "plugins"];
+	let read = ["external", "plugins", "preserveSymlinks"];
 	return Object.keys(cfg).reduce((memo, key) => {
 		let type = read.includes(key) ? "readConfig" : "writeConfig";
 		memo[type][key] = cfg[key];
diff --git a/test/unit/fixtures/external/cjs-module/index.js b/test/unit/fixtures/external/cjs-module/index.js
new file mode 100644
index 0000000..785a4fc
--- /dev/null
+++ b/test/unit/fixtures/external/cjs-module/index.js
@@ -0,0 +1,3 @@
+exports.dummy = {
+	some: "dummy value"
+};
diff --git a/test/unit/fixtures/src/import-symlinked.js b/test/unit/fixtures/src/import-symlinked.js
new file mode 100644
index 0000000..08813b1
--- /dev/null
+++ b/test/unit/fixtures/src/import-symlinked.js
@@ -0,0 +1,3 @@
+import { dummy } from "some-cjs-module";
+
+console.log(dummy); // eslint-disable-line no-console
diff --git a/test/unit/test_bundling.js b/test/unit/test_bundling.js
index c3f7d39..7da6d48 100644
--- a/test/unit/test_bundling.js
+++ b/test/unit/test_bundling.js
@@ -3,6 +3,7 @@
 
 let { MockAssetManager, makeBundle, FIXTURES_DIR } = require("./util");
 let faucetJS = require("../../lib").plugin;
+const fs = require("fs");
 let path = require("path");
 let assert = require("assert");
 
@@ -412,4 +413,49 @@ console.log(\`[DUMMY] $\{util}\`); // eslint-disable-line no-console
 				assetManager.assertWriteCount(1);
 			});
 	});
+
+	describe("working with linked modules", () => {
+		// in case some set this env variable before
+		let initialFlagValue = process.env.FAUCET_EXPERIMENTAL_SYMLINKS;
+
+		beforeEach(() => {
+			fs.symlinkSync(
+					path.resolve(FIXTURES_DIR, "./external/cjs-module"),
+					path.resolve(FIXTURES_DIR, "./node_modules/some-cjs-module"),
+					"dir"
+			);
+
+			process.env.FAUCET_EXPERIMENTAL_SYMLINKS = "true";
+		});
+
+		afterEach(() => {
+			fs.unlinkSync(path.resolve(FIXTURES_DIR, "./node_modules/some-cjs-module"));
+			process.env.FAUCET_EXPERIMENTAL_SYMLINKS = initialFlagValue;
+		});
+
+		it("should preserve symlinks when env varialbe is set", () => {
+			let config = [{
+				source: "./src/import-symlinked.js",
+				target: "./dist/bundle.js",
+				format: "CommonJS"
+			}];
+			let assetManager = new MockAssetManager(FIXTURES_DIR);
+
+			return faucetJS(config, assetManager, DEFAULT_OPTIONS)().
+				then(() => {
+					assetManager.assertWrites([{
+						filepath: path.resolve(FIXTURES_DIR, "./dist/bundle.js"),
+						content: makeBundle(`
+'use strict';
+
+var dummy = {
+	some: "dummy value"
+};
+
+console.log(dummy); // eslint-disable-line no-console
+`)
+					}]);
+				});
+		});
+	});
 });