fix(builtin): under runfiles linker should link node_modules folder at root of runfiles tree

Current it is link node_modules folder in the cwd which is `runfiles/wksp/node_modules` but this location means that script in external repositories such as `runfiles/external_wksp/path/to/script.js` will not resolve packages. This PR changes the linker to link to `runfiles/node_modules`.

Author: gregmagolan

internal/linker/index.js

@@ -112,6 +112,11 @@ Include as much of the build output as you can without disclosing anything confi
      */
     function resolveRoot(root, runfiles) {
         return __awaiter(this, void 0, void 0, function* () {
+            if (!runfiles.execroot) {
+                // Under runfiles, the repository should be layed out in the parent directory
+                // since bazel sets our working directory to the repository where the build is happening
+                process.chdir('..');
+            }
             // create a node_modules directory if no root
             // this will be the case if only first-party modules are installed
             if (!root) {
@@ -135,7 +140,7 @@ Include as much of the build output as you can without disclosing anything confi
             else {
                 // Under runfiles, the repository should be layed out in the parent directory
                 // since bazel sets our working directory to the repository where the build is happening
-                return path.join('..', root);
+                return root;
             }
         });
     }
@@ -425,12 +430,14 @@ Include as much of the build output as you can without disclosing anything confi
             const [modulesManifest] = args;
             let { bin, root, modules, workspace } = JSON.parse(fs.readFileSync(modulesManifest));
             modules = modules || {};
-            log_verbose(`module manifest '${modulesManifest}': workspace ${workspace}, bin ${bin}, root ${root} with first-party packages\n`, modules);
+            log_verbose('manifest file', modulesManifest);
+            log_verbose('manifest contents', JSON.stringify({ workspace, bin, root, modules }, null, 2));
+            // Bazel starts actions with pwd=execroot/my_wksp
+            const workspaceDir = path.resolve('.');
+            // resolveRoot will change the cwd when under runfiles
             const rootDir = yield resolveRoot(root, runfiles);
             log_verbose('resolved root', root, 'to', rootDir);
             log_verbose('cwd', process.cwd());
-            // Bazel starts actions with pwd=execroot/my_wksp
-            const workspaceDir = path.resolve('.');
             // Create the $pwd/node_modules directory that node will resolve from
             yield symlink(rootDir, 'node_modules');
             process.chdir(rootDir);

internal/linker/link_node_modules.ts

@@ -95,6 +95,11 @@ async function symlink(target: string, p: string): Promise<boolean> {
  * @param root a string like 'npm/node_modules'
  */
 async function resolveRoot(root: string|undefined, runfiles: Runfiles) {
+  if (!runfiles.execroot) {
+    // Under runfiles, the repository should be layed out in the parent directory
+    // since bazel sets our working directory to the repository where the build is happening
+    process.chdir('..');
+  }
   // create a node_modules directory if no root
   // this will be the case if only first-party modules are installed
   if (!root) {
@@ -118,7 +123,7 @@ async function resolveRoot(root: string|undefined, runfiles: Runfiles) {
   } else {
     // Under runfiles, the repository should be layed out in the parent directory
     // since bazel sets our working directory to the repository where the build is happening
-    return path.join('..', root);
+    return root;
   }
 }
 
@@ -485,18 +490,17 @@ export async function main(args: string[], runfiles: Runfiles) {
   const [modulesManifest] = args;
   let {bin, root, modules, workspace} = JSON.parse(fs.readFileSync(modulesManifest));
   modules = modules || {};
-  log_verbose(
-      `module manifest '${modulesManifest}': workspace ${workspace}, bin ${bin}, root ${
-          root} with first-party packages\n`,
-      modules);
+  log_verbose('manifest file', modulesManifest);
+  log_verbose('manifest contents', JSON.stringify({workspace, bin, root, modules}, null, 2));
 
+  // Bazel starts actions with pwd=execroot/my_wksp
+  const workspaceDir = path.resolve('.');
+
+  // resolveRoot will change the cwd when under runfiles
   const rootDir = await resolveRoot(root, runfiles);
   log_verbose('resolved root', root, 'to', rootDir);
   log_verbose('cwd', process.cwd());
 
-  // Bazel starts actions with pwd=execroot/my_wksp
-  const workspaceDir = path.resolve('.');
-
   // Create the $pwd/node_modules directory that node will resolve from
   await symlink(rootDir, 'node_modules');
   process.chdir(rootDir);

internal/linker/test/link_node_modules.spec.ts

@@ -532,6 +532,6 @@ describe('link_node_modules', () => {
 
     // The linker expects to run as its own process, so it changes the wd
     process.chdir(path.join(process.env['TEST_TMPDIR']!, workspace));
-    expect(fs.readdirSync(path.join('node_modules', 'some-package'))).toContain('index.js');
+    expect(fs.readdirSync(path.join('..', 'node_modules', 'some-package'))).toContain('index.js');
   });
 });