From 7ab2b36495db70c75522bbe27a40c10b81bf849f Mon Sep 17 00:00:00 2001
From: Claude Bot <claude-bot@bun.sh>
Date: Sun, 1 Feb 2026 06:05:45 +0000
Subject: [PATCH] test(bundler): add regression test for plugin transform
 import.meta.url

Add a regression test for GitHub issue #26653 which reported that
transitive dependencies could incorrectly use real filesystem paths
instead of virtual /$bunfs/ paths in standalone builds when a plugin
transforms files.

The test verifies that when a plugin's onLoad callback transforms a
file, the transitive dependencies (files imported by the transformed
file) still correctly have import.meta.url pointing to the virtual
filesystem path rather than the original filesystem path.

Testing shows the basic behavior is correct - this test ensures it
stays that way. The original issue may only manifest in very large
codebases (70+ transformed files).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 test/bundler/bundler_compile.test.ts | 61 ++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/test/bundler/bundler_compile.test.ts b/test/bundler/bundler_compile.test.ts
index 28cea068e0..1b613eec9a 100644
--- a/test/bundler/bundler_compile.test.ts
+++ b/test/bundler/bundler_compile.test.ts
@@ -935,4 +935,65 @@ const server = serve({
     const result = await Bun.$`./app`.cwd(dir).env(bunEnv).nothrow();
     expect(result.stdout.toString().trim()).toBe("IT WORKS");
   });
+
+  // Regression test for https://github.com/oven-sh/bun/issues/26653
+  // When a plugin transforms a file's content, transitive dependencies should
+  // still have correct import.meta.url pointing to the virtual /$bunfs/ path,
+  // not the original filesystem path.
+  itBundled("compile/PluginTransformPreservesTransitiveImportMetaUrl", {
+    compile: true,
+    backend: "api",
+    outfile: "dist/out",
+    files: {
+      "/entry.ts": /* js */ `
+        import { processData } from "./model.ts";
+        const result = processData();
+        console.log("Result:", result);
+      `,
+      "/model.ts": /* js */ `
+        // This file is transformed by a plugin - it uses a placeholder
+        // that gets replaced with the actual filesystem path
+        import { helper } from "./utils.ts";
+        const MODEL_URL = "MODEL_URL_PLACEHOLDER";
+        export function processData() {
+          console.log("Model URL:", MODEL_URL);
+          return helper();
+        }
+      `,
+      "/utils.ts": /* js */ `
+        // This transitive dependency is NOT transformed by the plugin.
+        // Its import.meta.url should point to the virtual /$bunfs/ path,
+        // not the original filesystem path.
+        export function helper() {
+          const url = import.meta.url;
+          console.log("Utils URL:", url);
+          // Verify the URL is the virtual path
+          if (url.includes("/$bunfs/") || url.includes("B:\\\\~BUN\\\\")) {
+            return "success";
+          } else {
+            return "FAIL: import.meta.url is not virtual path: " + url;
+          }
+        }
+      `,
+    },
+    plugins: [
+      {
+        name: "transform-model",
+        setup(api) {
+          api.onLoad({ filter: /model\.ts$/ }, async args => {
+            const { pathToFileURL } = await import("url");
+            const contents = await Bun.file(args.path).text();
+            // Replace placeholder with actual filesystem path
+            const fileUrl = pathToFileURL(args.path).href;
+            const transformed = contents.replace("MODEL_URL_PLACEHOLDER", fileUrl);
+            return { contents: transformed, loader: "ts" };
+          });
+        },
+      },
+    ],
+    run: {
+      // The output should show success from utils.ts, verifying import.meta.url is correct
+      stdout: /Result: success/,
+    },
+  });
 });