Adds tests

sources/commands/Hydrate.ts

@@ -23,8 +23,8 @@ export class HydrateCommand extends Command<Context> {
     @Command.Path(`hydrate`)
     async execute() {
         const installFolder = folderUtils.getInstallFolder();
-        const fileName = path.resolve(this.context.cwd);
+        const fileName = path.resolve(this.context.cwd, this.fileName);
 
-        await tar.x({file: fileName, strip: 1, cwd: installFolder});
+        await tar.x({file: fileName, cwd: installFolder});
     }
 }

sources/folderUtils.ts

@@ -3,7 +3,7 @@ import {homedir, tmpdir} from 'os';
 import {join}            from 'path';
 
 export function getInstallFolder() {
-    return join(homedir(), `.node/pmm`);
+    return process.env.PMM_HOME ?? join(homedir(), `.node/pmm`);
 }
 
 export function getTemporaryFolder(target: string = tmpdir()) {

sources/httpUtils.ts

@@ -1,7 +1,11 @@
+import {UsageError} from 'clipanion';
 import https, {RequestOptions} from 'https';
 import {IncomingMessage} from 'http';
 
 export function fetchUrlStream(url: string, options: RequestOptions = {}) {
+    if (process.env.PMM_ENABLE_NETWORK === `0`)
+        throw new UsageError(`Network access disabled by the environment; can't reach ${url}`);
+
     return new Promise<IncomingMessage>((resolve, reject) => {
         const request = https.get(url, options, response => {
             const statusCode = response.statusCode ?? 500;

tests/_runCli.ts

@@ -1,6 +1,7 @@
 import {PortablePath, npath} from '@yarnpkg/fslib';
 import {PassThrough}         from 'stream';
 
+import {Engine} from '../sources/Engine';
 import {main} from '../sources/main';
 
 export async function runCli(cwd: PortablePath, argv: string[]) {
@@ -21,6 +22,7 @@ export async function runCli(cwd: PortablePath, argv: string[]) {
 
     const exitCode = await main(argv, {
         cwd: npath.fromPortablePath(cwd),
+        engine: new Engine(),
         stdin,
         stdout,
         stderr,

tests/main.test.ts

@@ -1,9 +1,13 @@
-import {Filename, ppath, xfs} from '@yarnpkg/fslib';
+import {Filename, ppath, xfs, PortablePath} from '@yarnpkg/fslib';
 import Enquirer               from 'enquirer';
 
 import config                 from '../config.json';
 import {runCli}               from './_runCli';
 
+beforeEach(async () => {
+    process.env.PMM_HOME = await xfs.mktempPromise();
+});
+
 for (const [name, version] of [[`yarn`, `1.22.4`], [`yarn`, `2.0.0-rc.30`], [`pnpm`, `4.11.6`], [`npm`, `6.14.2`]]) {
     it(`should use the right package manager version for a given project (${name}@${version})`, async () => {
         await xfs.mktempPromise(async cwd => {
@@ -76,3 +80,54 @@ it(`should use the pinned version when local projects don't list any spec`, asyn
         });
     });
 });
+
+it(`should support disabling the network accesses from the environment`, async () => {
+    process.env.PMM_ENABLE_NETWORK = `0`;
+
+    try {
+        await xfs.mktempPromise(async cwd => {
+            await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+                packageManager: `yarn@2.2.2`,
+            });
+
+            await expect(runCli(cwd, [`yarn`, `yarn`, `--version`])).resolves.toMatchObject({
+                stdout: expect.stringContaining(`Network access disabled by the environment`),
+                exitCode: 1,
+            });
+        });
+    } finally {
+        delete process.env.PMM_ENABLE_NETWORK;
+    }
+});
+
+it(`should support hydrating package managers from cached archives`, async () => {
+    await xfs.mktempPromise(async cwd => {
+        await expect(runCli(cwd, [`pack`, `yarn@2.2.2`])).resolves.toMatchObject({
+            exitCode: 0,
+        });
+
+        // Use a new cache
+        process.env.PMM_HOME = await xfs.mktempPromise();
+
+        // Disable the network to make sure we don't succeed by accident
+        process.env.PMM_ENABLE_NETWORK = `0`;
+
+        try {
+            await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+                packageManager: `yarn@2.2.2`,
+            });
+
+            await expect(runCli(cwd, [`hydrate`, `pmm-yarn-2.2.2.tgz`])).resolves.toMatchObject({
+                stdout: ``,
+                exitCode: 0,
+            });
+
+            await expect(runCli(cwd, [`yarn`, `yarn`, `--version`])).resolves.toMatchObject({
+                stdout: `2.2.2\n`,
+                exitCode: 0,
+            });
+        } finally {
+            delete process.env.PMM_ENABLE_NETWORK;
+        }
+    });
+});