fix: handle external deps with tsconfig baseUrl

Author: tbjgolden

.env

@@ -0,0 +1 @@
+TEST=value

lib/__fixtures__/dotenv-test/index.ts

@@ -0,0 +1,3 @@
+import 'dotenv/config';
+
+console.log(process.env.TEST)

lib/__fixtures__/dotenv-test/tsconfig.json

@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "baseUrl": "."
+  }
+}

lib/createSourceFileTree.ts

@@ -1,6 +1,7 @@
 import fs from "node:fs";
+import { createRequire } from "node:module";
 import fsPath from "node:path";
-import { fileURLToPath } from "node:url";
+import { fileURLToPath, pathToFileURL } from "node:url";
 
 import { Expression, Literal, Program } from "acorn";
 import { simple } from "acorn-walk";
@@ -167,11 +168,23 @@ const createSourceFileTreeRecursive = ({
       }
     }
     if (firstError) {
-      throw new XnrError(
-        `Could not find import:\n  ${prettyPath(rawImport.importPath)}\nfrom:\n  ${prettyPath(
-          absResolvedPath
-        )}`
-      );
+      // This can be reached is an npm dependency is also a valid local path
+      // e.g. when tsconfig has baseUrl set
+      // So we only error if it is not a resolvable npm dependency
+      try {
+        let { importPath } = rawImport;
+        if (importPath.startsWith("file://")) {
+          importPath = fileURLToPath(importPath);
+        }
+        createRequire(pathToFileURL(absResolvedPath)).resolve(importPath);
+        return [];
+      } catch {
+        throw new XnrError(
+          `Could not find import:\n  ${prettyPath(rawImport.importPath)}\nfrom:\n  ${prettyPath(
+            absResolvedPath
+          )}`
+        );
+      }
     }
     throw new Error("Unreachable");
   });

lib/run.test.ts

@@ -118,6 +118,24 @@ test("run a file directly (success with stdout)", async () => {
   expect(stderr).toBe("");
 });
 
+test("run a file directly (dotenv)", async () => {
+  let stdout = "";
+  let stderr = "";
+  await expect(
+    run({
+      filePath: "lib/__fixtures__/dotenv-test/index.ts",
+      onWriteStdout: (out) => {
+        stdout += out;
+      },
+      onWriteStderr: (err) => {
+        stderr += err;
+      },
+    })
+  ).resolves.toBe(0);
+  expect(stdout).toBe("value\n");
+  expect(stderr).toBe("");
+});
+
 test("run a file directly (ansi escape)", async () => {
   let stdout = "";
   let stderr = "";