feat(plugin-pack): reload manifest after prepack script

.yarn/versions/ad4d146d.yml

@@ -0,0 +1,8 @@
+releases:
+  "@yarnpkg/cli": major
+  "@yarnpkg/plugin-pack": minor
+
+declined:
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-typescript"

packages/acceptance-tests/pkg-tests-specs/sources/commands/pack.test.js

@@ -610,5 +610,57 @@ describe(`Commands`, () => {
         expect(stdout).not.toMatch(/src\/a\.ts/);
       }),
     );
+
+    test(
+      `it should reflect changes made to package.json during prepack`,
+      makeTemporaryEnv({
+        workspaces: [`./dependency`, `./dependant`],
+      }, async({path, run, source}) => {
+        const dependency = `@test/dependency`;
+        const dependant = `@test/dependant`;
+
+        await fsUtils.writeJson(`${path}/dependency/package.json`, {
+          name: dependency,
+          version: `1.0.0`,
+        });
+
+        const packageJson = {
+          name: dependant,
+          version: `1.0.0`,
+          scripts: {
+            prepack: `cp package.json package.json.bak && cp package.json.tmp package.json`,
+            postpack: `mv package.json.bak package.json`,
+          },
+          devDependencies: {
+            [dependency]: `workspace:*`,
+          },
+        };
+
+        await fsUtils.writeJson(`${path}/dependant/package.json`, packageJson);
+        await fsUtils.writeJson(`${path}/dependant/package.json.tmp`, {
+          ...packageJson,
+          dependencies: {
+            [dependency]: `workspace:^1.0.0`,
+          },
+        });
+
+        await run(`install`);
+        await run(`pack`, {
+          cwd: `${path}/dependant`,
+        });
+
+        await fsUtils.unpackToDirectory(path, `${path}/dependant/package.tgz`);
+
+        const packedManifest = await fsUtils.readJson(`${path}/package/package.json`);
+
+        expect(packedManifest.dependencies[dependency]).toBe(`^1.0.0`);
+        expect(packedManifest.devDependencies[dependency]).toBe(`1.0.0`);
+
+        const originalManifest = await fsUtils.readJson(`${path}/dependant/package.json`);
+
+        expect(originalManifest.dependencies).toBe(undefined);
+        expect(originalManifest.devDependencies[dependency]).toBe(`workspace:*`);
+      }),
+    );
   });
 });

packages/plugin-pack/sources/packUtils.ts

@@ -1,4 +1,4 @@
-import {Report, Workspace, scriptUtils, tgzUtils}                  from '@yarnpkg/core';
+import {Manifest, Report, Workspace, scriptUtils, tgzUtils}        from '@yarnpkg/core';
 import {FakeFS, JailFS, xfs, PortablePath, ppath, Filename, npath} from '@yarnpkg/fslib';
 import {Hooks as StageHooks}                                       from '@yarnpkg/plugin-stage';
 import mm                                                          from 'micromatch';
@@ -57,6 +57,10 @@ export async function prepareForPack(workspace: Workspace, {report}: {report: Re
   await scriptUtils.maybeExecuteWorkspaceLifecycleScript(workspace, `prepack`, {report});
 
   try {
+    const manifestPath = ppath.join(workspace.cwd, Manifest.fileName);
+    if (await xfs.existsPromise(manifestPath))
+      await workspace.manifest.loadFile(manifestPath, {baseFs: xfs});
+
     await cb();
   } finally {
     await scriptUtils.maybeExecuteWorkspaceLifecycleScript(workspace, `postpack`, {report});