Correctly resolve peerDependencies for concurrent installs (#2801)

* Correctly resolve peerDependencies for concurrent installs

* Tests for resolving peerDependencies when using add command

__tests__/commands/add.js

@@ -1,6 +1,7 @@
 /* @flow */
 
 import {ConsoleReporter} from '../../src/reporters/index.js';
+import * as reporters from '../../src/reporters/index.js';
 import {getPackageVersion, createLockfile, explodeLockfile, run as buildRun, runInstall} from './_helpers.js';
 import {Add} from '../../src/cli/commands/add.js';
 import * as constants from '../../src/constants.js';
@@ -702,3 +703,55 @@ test.concurrent('install with latest tag and --prefer-offline flag', (): Promise
     assert.notEqual(version, '1.1.0');
   });
 });
+
+test.concurrent('doesn\'t warn when peer dependency is met during add', (): Promise<void> => {
+  return buildRun(
+    reporters.BufferReporter,
+    fixturesLoc,
+    async (args, flags, config, reporter, lockfile): Promise<void> => {
+      const add = new Add(args, flags, config, reporter, lockfile);
+      await add.init();
+      const output = reporter.getBuffer();
+      const warnings = output.filter((entry) => entry.type === 'warning');
+      assert(!warnings.some((warning) => warning.data.toString().toLowerCase().includes('unmet peer')));
+      assert(!warnings.some((warning) => warning.data.toString().toLowerCase().includes('incorrect peer')));
+    },
+    ['[email protected]', '[email protected]'],
+    {},
+    'add-with-peer-dependency-met',
+  );
+});
+
+test.concurrent('warns when peer dependency is not met during add', (): Promise<void> => {
+  return buildRun(
+    reporters.BufferReporter,
+    fixturesLoc,
+    async (args, flags, config, reporter, lockfile): Promise<void> => {
+      const add = new Add(args, flags, config, reporter, lockfile);
+      await add.init();
+      const output = reporter.getBuffer();
+      const warnings = output.filter((entry) => entry.type === 'warning');
+      assert(warnings.some((warning) => warning.data.toString().toLowerCase().includes('unmet peer')));
+    },
+    ['[email protected]'],
+    {},
+    'add-with-peer-dependency-not-met',
+  );
+});
+
+test.concurrent('warns when peer dependency is incorrect during add', (): Promise<void> => {
+  return buildRun(
+    reporters.BufferReporter,
+    fixturesLoc,
+    async (args, flags, config, reporter, lockfile): Promise<void> => {
+      const add = new Add(args, flags, config, reporter, lockfile);
+      await add.init();
+      const output = reporter.getBuffer();
+      const warnings = output.filter((entry) => entry.type === 'warning');
+      assert(warnings.some((warning) => warning.data.toString().toLowerCase().includes('incorrect peer')));
+    },
+    ['[email protected]', '[email protected]'],
+    {},
+    'add-with-peer-dependency-incorrect',
+  );
+});

src/package-linker.js

@@ -288,48 +288,16 @@ export default class PackageLinker {
 
     for (const name in peerDeps) {
       const range = peerDeps[name];
-
-      // find a dependency in the tree above us that matches
-      let searchPatterns: Array<string> = [];
-      for (let request of ref.requests) {
-        do {
-          // get resolved pattern for this request
-          const dep = this.resolver.getResolvedPattern(request.pattern);
-          if (!dep) {
-            continue;
-          }
-
-          //
-          const ref = dep._reference;
-          invariant(ref, 'expected reference');
-          searchPatterns = searchPatterns.concat(ref.dependencies);
-        } while (request = request.parentRequest);
-      }
-
-      // if the resolver already knows about the peer dependency, add those patterns as well
-      const packagePatterns = this.resolver.patternsByPackage[name];
-      if (packagePatterns) {
-        searchPatterns = searchPatterns.concat(packagePatterns);
-      }
-
-      // include root seed patterns last
-      searchPatterns = searchPatterns.concat(this.resolver.seedPatterns);
-
-      // find matching dep in search patterns
-      let foundDep: ?{pattern: string, version: string};
-      for (const pattern of searchPatterns) {
-        const dep = this.resolver.getResolvedPattern(pattern);
-        if (dep && dep.name === name) {
-          foundDep = {pattern, version: dep.version};
-          break;
-        }
-      }
-
-      // validate found peer dependency
-      if (foundDep && this._satisfiesPeerDependency(range, foundDep.version)) {
-        ref.addDependencies([foundDep.pattern]);
+      const patterns = this.resolver.patternsByPackage[name] || [];
+      const foundPattern = patterns.find((pattern) => {
+        const resolvedPattern = this.resolver.getResolvedPattern(pattern);
+        return resolvedPattern ? this._satisfiesPeerDependency(range, resolvedPattern.version) : false;
+      });
+
+      if (foundPattern) {
+        ref.addDependencies([foundPattern]);
       } else {
-        const depError = foundDep ? 'incorrectPeer' : 'unmetPeer';
+        const depError = patterns.length > 0 ? 'incorrectPeer' : 'unmetPeer';
         const [pkgHuman, depHuman] = [`${pkg.name}@${pkg.version}`, `${name}@${range}`];
         this.reporter.warn(this.reporter.lang(depError, pkgHuman, depHuman));
       }