fix: set conditional exports in package.json (#299)

Co-authored-by: Oliver Dowling <[email protected]>

package.json

@@ -5,6 +5,14 @@
     "main": "lib/node/index.js",
     "browser": "lib/browser/index.js",
     "types": "lib/types/index.d.ts",
+    "exports": {
+        ".": {
+            "types": "./lib/types/index.d.ts",
+            "node": "./lib/node/index.js",
+            "default": "./lib/browser/index.js"
+        },
+        "./package.json": "./package.json"
+    },
     "sideEffects": false,
     "type": "module",
     "files": [

test/packageJSON.spec.ts

@@ -0,0 +1,30 @@
+import { readFileSync, existsSync } from "node:fs";
+import { it } from "mocha";
+import { expect } from "chai";
+
+function getPathsFromPackageJSON(): string[] {
+    const packageJSON = JSON.parse(readFileSync("package.json", "utf-8"));
+
+    const flatten = (obj: unknown): string[] => {
+        if (typeof obj !== "object" || !obj) {
+            return [];
+        }
+
+        const values = Object.values(obj);
+        return values.flatMap((value) => (typeof value === "string" ? [value] : flatten(value)));
+    };
+
+    const paths = [packageJSON["main"], packageJSON["browser"], packageJSON["types"], ...flatten(packageJSON["exports"])];
+
+    return paths;
+}
+
+describe("package.json", () => {
+    it("all entry points exist", () => {
+        const paths = getPathsFromPackageJSON();
+
+        for (const path of paths) {
+            expect(existsSync(path), `Path ${path} does not exist`).to.be.true;
+        }
+    });
+});