Issue yarnpkg#570 Make install pure by default

__tests__/commands/install.js

@@ -49,14 +49,18 @@ test.concurrent('flat arg is inherited from root manifest', async (): Promise<vo
 
 
 test.concurrent("doesn't write new lockfile if existing one satisfied", (): Promise<void> => {
-  return runInstall({}, 'install-dont-write-lockfile-if-satisfied', async (config): Promise<void> => {
-    const lockfile = await fs.readFile(path.join(config.cwd, 'yarn.lock'));
-    assert(lockfile.indexOf('foobar') >= 0);
-  });
+  return runInstall(
+    {writeLockfile: true},
+    'install-dont-write-lockfile-if-satisfied',
+    async (config): Promise<void> => {
+      const lockfile = await fs.readFile(path.join(config.cwd, 'yarn.lock'));
+      assert(lockfile.indexOf('foobar') >= 0);
+    },
+  );
 });
 
 test.concurrent("writes new lockfile if existing one isn't satisfied", async (): Promise<void> => {
-  await runInstall({}, 'install-write-lockfile-if-not-satisfied', async (config): Promise<void> => {
+  await runInstall({writeLockfile: true}, 'install-write-lockfile-if-not-satisfied', async (config): Promise<void> => {
     const lockfile = await fs.readFile(path.join(config.cwd, 'yarn.lock'));
     assert(lockfile.indexOf('foobar') === -1);
   });
@@ -393,7 +397,7 @@ test.concurrent(
   (): Promise<void> => {
     const mirrorPath = 'mirror-for-offline';
 
-    return runInstall({}, 'uninstall-should-clean', async (config, reporter) => {
+    return runInstall({writeLockfile: true}, 'uninstall-should-clean', async (config, reporter) => {
       assert.equal(
         await getPackageVersion(config, 'dep-a'),
         '1.0.0',
@@ -557,9 +561,9 @@ test.concurrent('install should resolve circular dependencies 2', (): Promise<vo
 });
 
 test.concurrent(
-  'install should add missing deps to yarn and mirror (PR import scenario)',
+  'install should add missing deps to yarn and mirror when given --write-lockfile (PR import scenario)',
   (): Promise<void> => {
-    return runInstall({}, 'install-import-pr', async (config) => {
+    return runInstall({writeLockfile: true}, 'install-import-pr', async (config) => {
       assert.equal(await getPackageVersion(config, 'mime-types'), '2.0.0');
       assert(semver.satisfies(await getPackageVersion(config, 'mime-db'), '~1.0.1'));
       assert.equal(await getPackageVersion(config, 'fake-yarn-dependency'), '1.0.1');
@@ -579,7 +583,6 @@ test.concurrent(
   },
 );
 
-
 xit('install should update a dependency to yarn and mirror (PR import scenario 2)', (): Promise<void> => {
   // mime-types@2.0.0 is saved in local mirror and gets updated to mime-types@2.1.11 via
   // a change in package.json,

src/cli/commands/add.js

@@ -23,6 +23,7 @@ export class Add extends Install {
   ) {
     super(flags, config, reporter, lockfile);
     this.args = args;
+    this.flags.writeLockfile = true;
   }
 
   args: Array<string>;

src/cli/commands/install.js

@@ -59,7 +59,7 @@ type Flags = {
   flat: boolean,
   production: boolean,
   lockfile: boolean,
-  pureLockfile: boolean,
+  writeLockfile: boolean,
   skipIntegrity: boolean,
 
   // add
@@ -82,7 +82,7 @@ function normalizeFlags(config: Config, rawFlags: Object): Flags {
     flat: !!rawFlags.flat,
     production: !!rawFlags.production,
     lockfile: rawFlags.lockfile !== false,
-    pureLockfile: !!rawFlags.pureLockfile,
+    writeLockfile: !!rawFlags.writeLockfile,
     skipIntegrity: !!rawFlags.skipIntegrity,
 
     // add
@@ -354,8 +354,12 @@ export class Install {
       await step(++currentStep, steps.length);
     }
 
-    // fin!
-    await this.saveLockfileAndIntegrity(rawPatterns);
+    // Write lockfile if none exist, or if flag given
+    const lockfileLoc = path.join(this.config.cwd, constants.LOCKFILE_FILENAME);
+    if (!(await fs.exists(lockfileLoc)) || this.flags.writeLockfile) {
+      await this.saveLockfileAndIntegrity(rawPatterns);
+    }
+
     this.config.requestManager.clearCache();
     return patterns;
   }
@@ -472,8 +476,8 @@ export class Install {
     // write integrity hash
     await this.writeIntegrityHash(lockSource, patterns);
 
-    // --no-lockfile or --pure-lockfile flag
-    if (this.flags.lockfile === false || this.flags.pureLockfile) {
+    // --no-lockfile flag
+    if (this.flags.lockfile === false) {
       return;
     }
 
@@ -653,7 +657,7 @@ export function _setFlags(commander: Object) {
   commander.option('--flat', 'only allow one version of a package');
   commander.option('--prod, --production', '');
   commander.option('--no-lockfile', "don't read or generate a lockfile");
-  commander.option('--pure-lockfile', "don't generate a lockfile");
+  commander.option('--write-lockfile', 'generate a lockfile');
 }
 
 export function setFlags(commander: Object) {

src/cli/commands/remove.js

@@ -76,7 +76,7 @@ export async function run(
 
   // reinstall so we can get the updated lockfile
   reporter.step(++step, totalSteps, reporter.lang('uninstallRegenerate'));
-  const reinstall = new Install({force: true, ...flags}, config, new NoopReporter(), lockfile);
+  const reinstall = new Install({force: true, writeLockfile: true, ...flags}, config, new NoopReporter(), lockfile);
   await reinstall.init();
 
   //