peerDep correctness

index.ts

@@ -3,6 +3,7 @@ import tmp = require('tmp');
 import fs = require('fs-extra');
 import path = require('path');
 import resolvePackagePath = require('resolve-package-path');
+import CacheGroup = require('resolve-package-path/lib/cache-group');
 import { PackageJson } from 'type-fest';
 import { readdirSync, statSync } from 'fs';
 
@@ -127,6 +128,12 @@ export class Project {
 
   private dependencyLinks: Map<string, { dir: string; requestedRange: string }> = new Map();
   private linkIsDevDependency: Set<string> = new Set();
+  private usingHardLinks = true;
+
+  // we keep our own package resolution cache because the default global one
+  // could get polluted by us resolving test-specific things that will change on
+  // subsequent tests.
+  private resolutionCache = new CacheGroup();
 
   constructor(
     name?: string,
@@ -262,7 +269,7 @@ export class Project {
   }
 
   private writeLinkedPackage(name: string, target: string) {
-    let targetPkg = require(path.join(target, 'package.json'));
+    let targetPkg = fs.readJsonSync(`${target}/package.json`);
     let peers = new Set(Object.keys(targetPkg.peerDependencies ?? {}));
     let destination = path.join(this.baseDir, 'node_modules', name);
 
@@ -281,7 +288,7 @@ export class Project {
           if (peers.has(depName)) {
             continue;
           }
-          let depTarget = resolvePackagePath(depName, target);
+          let depTarget = resolvePackagePath(depName, target, this.resolutionCache);
           if (!depTarget) {
             throw new Error(`package ${name} in ${target} depends on ${depName} but we could not resolve it`);
           }
@@ -303,9 +310,24 @@ export class Project {
       if (stat.isDirectory()) {
         this.hardLinkContents(path.join(target, name), path.join(destination, name));
       } else {
-        fs.ensureLinkSync(path.join(target, name), path.join(destination, name));
+        this.hardLinkFile(path.join(target, name), path.join(destination, name));
+      }
+    }
+  }
+
+  private hardLinkFile(source: string, destination: string) {
+    if (this.usingHardLinks) {
+      try {
+        fs.ensureLinkSync(source, destination);
+        return;
+      } catch (err: any) {
+        if (err.code !== 'EXDEV') {
+          throw err;
+        }
+        this.usingHardLinks = false;
       }
     }
+    fs.copySync(source, destination);
   }
 
   static fromDir(root: string, opts?: ReadDirOpts): Project {
@@ -482,7 +504,7 @@ export class Project {
     this.removeDevDependency(name);
     let dir: string;
     if ('baseDir' in opts) {
-      let pkgJSONPath = resolvePackagePath(opts.resolveName || name, opts.baseDir);
+      let pkgJSONPath = resolvePackagePath(opts.resolveName || name, opts.baseDir, this.resolutionCache);
       if (!pkgJSONPath) {
         throw new Error(`failed to locate ${opts.resolveName || name} in ${opts.baseDir}`);
       }