Add test-exports case for CJS dynamic import (langchain-ai#179)

Since we have this in the docs, we should test it (it does work)

test-exports/index.cjs

@@ -0,0 +1,50 @@
+async function test() {
+  const { default: assert } = await import("assert");
+  const { OpenAI } = await import("langchain");
+  const { loadPrompt } = await import("langchain/prompts");
+  const { HNSWLib } = await import("langchain/vectorstores");
+  const { OpenAIEmbeddings } = await import("langchain/embeddings");
+  const { InMemoryDocstore, Document } = await import("langchain/docstore");
+
+  // Test exports
+  assert(typeof OpenAI === "function");
+  assert(typeof loadPrompt === "function");
+  assert(typeof HNSWLib === "function");
+
+  // Test dynamic imports of peer dependencies
+  const { HierarchicalNSW } = await HNSWLib.imports();
+
+  const vs = new HNSWLib(
+    {
+      space: "ip",
+      numDimensions: 3,
+    },
+    new OpenAIEmbeddings({ openAIApiKey: "sk-XXXX" }),
+    new InMemoryDocstore(),
+    new HierarchicalNSW("ip", 3)
+  );
+
+  await vs.addVectors(
+    [
+      [0, 1, 0],
+      [0, 0, 1],
+    ],
+    [
+      new Document({
+        pageContent: "a",
+      }),
+      new Document({
+        pageContent: "b",
+      }),
+    ]
+  );
+
+  assert((await vs.similaritySearchVectorWithScore([0, 0, 1], 1)).length === 1);
+}
+
+test()
+  .then(() => console.log("success"))
+  .catch((e) => {
+    console.error(e);
+    process.exit(1);
+  });

test-exports/package.json

@@ -6,7 +6,7 @@
   "main": "./index.js",
   "type": "module",
   "scripts": {
-    "test": "node ./index.mjs && tsc",
+    "test": "node ./index.mjs && node ./index.cjs && tsc",
     "format": "prettier --write \"**/*.ts\"",
     "format:diff": "prettier --list-different \"**/*.ts\"",
     "ci": "yarn format:diff && yarn test"
@@ -21,4 +21,4 @@
     "prettier": "^2.8.3",
     "typescript": "^4.9.5"
   }
-}
+}