feat(init): Create .gitignore with lerna init

commands/init/README.md

@@ -18,6 +18,7 @@ When run, this command will:
 
 1. Add `lerna` as a [`devDependency`](https://docs.npmjs.com/files/package.json#devdependencies) in `package.json` if it doesn't already exist.
 2. Create a `lerna.json` config file to store the `version` number.
+3. Generate a `.gitignore` file if one doesn't already exist.
 
 Example output on a new git repo:
 

commands/init/__tests__/init-command.test.js

@@ -63,6 +63,17 @@ describe("InitCommand", () => {
       expect(gitDirExists).toBe(true);
     });
 
+    it("initializes .gitignore", async () => {
+      const testDir = tempy.directory();
+
+      await lernaInit(testDir)();
+
+      const gitIgnorePath = path.join(testDir, ".gitignore");
+      const gitIgnoreContent = await fs.readFile(gitIgnorePath, "utf8");
+
+      expect(gitIgnoreContent).toMatchInlineSnapshot(`"node_modules/"`);
+    });
+
     it("initializes git repo with lerna files in independent mode", async () => {
       const testDir = tempy.directory();
 
@@ -147,6 +158,21 @@ describe("InitCommand", () => {
     });
   });
 
+  describe("when .gitignore exists", () => {
+    it("does not change existing .gitignore", async () => {
+      const testDir = await tempy.directory();
+
+      const gitIgnorePath = path.join(testDir, ".gitignore");
+      await fs.writeFile(gitIgnorePath, "dist/");
+
+      await lernaInit(testDir)();
+
+      const gitIgnoreContent = await fs.readFile(gitIgnorePath, "utf8");
+
+      expect(gitIgnoreContent).toMatchInlineSnapshot(`"dist/"`);
+    });
+  });
+
   describe("when package.json exists", () => {
     it("adds lerna to sorted devDependencies", async () => {
       const testDir = await initFixture("has-package");

commands/init/index.js

@@ -42,6 +42,7 @@ class InitCommand extends Command {
   execute() {
     let chain = Promise.resolve();
 
+    chain = chain.then(() => this.ensureGitIgnore());
     chain = chain.then(() => this.ensureConfig());
     chain = chain.then(() => this.ensurePackagesDir());
 
@@ -51,6 +52,19 @@ class InitCommand extends Command {
     });
   }
 
+  ensureGitIgnore() {
+    const gitIgnorePath = path.join(this.project.rootPath, ".gitignore");
+
+    let chain = Promise.resolve();
+
+    if (!fs.existsSync(gitIgnorePath)) {
+      this.logger.info("", "Creating .gitignore");
+      chain = chain.then(() => fs.writeFile(gitIgnorePath, "node_modules/"));
+    }
+
+    return chain;
+  }
+
   ensureConfig() {
     const hasExistingLernaConfig = !!this.project.version;
     const hasExistingPackageJson = !!this.project.manifest;

e2e/tests/lerna-init/lerna-init.spec.ts

@@ -20,6 +20,7 @@ describe("lerna-init", () => {
     expect(output.stderr).toMatchInlineSnapshot(`
       "lerna notice cli v999.9.9-e2e.0
       lerna info Initializing Git repository
+      lerna info Creating .gitignore
       lerna info Creating package.json
       lerna info Creating lerna.json
       lerna info Creating packages directory
@@ -50,6 +51,7 @@ describe("lerna-init", () => {
       }
       "
     `);
+    expect(await fixture.readWorkspaceFile(".gitignore")).toMatchInlineSnapshot(`"node_modules/"`);
   });
 
   describe("--independent", () => {
@@ -59,6 +61,7 @@ describe("lerna-init", () => {
       expect(output.stderr).toMatchInlineSnapshot(`
         "lerna notice cli v999.9.9-e2e.0
         lerna info Initializing Git repository
+        lerna info Creating .gitignore
         lerna info Creating package.json
         lerna info Creating lerna.json
         lerna info Creating packages directory
@@ -89,6 +92,7 @@ describe("lerna-init", () => {
         }
         "
       `);
+      expect(await fixture.readWorkspaceFile(".gitignore")).toMatchInlineSnapshot(`"node_modules/"`);
     });
   });
 
@@ -99,6 +103,7 @@ describe("lerna-init", () => {
       expect(output.stderr).toMatchInlineSnapshot(`
         "lerna notice cli v999.9.9-e2e.0
         lerna info Initializing Git repository
+        lerna info Creating .gitignore
         lerna info Creating package.json
         lerna info Creating lerna.json
         lerna info Creating packages directory
@@ -134,6 +139,7 @@ describe("lerna-init", () => {
         }
         "
       `);
+      expect(await fixture.readWorkspaceFile(".gitignore")).toMatchInlineSnapshot(`"node_modules/"`);
     });
   });
 
@@ -144,6 +150,7 @@ describe("lerna-init", () => {
       expect(output.stderr).toMatchInlineSnapshot(`
         "lerna notice cli v999.9.9-e2e.0
         lerna info Initializing Git repository
+        lerna info Creating .gitignore
         lerna info Creating package.json
         lerna info Creating lerna.json
         lerna info Creating packages directory
@@ -179,6 +186,7 @@ describe("lerna-init", () => {
         }
         "
       `);
+      expect(await fixture.readWorkspaceFile(".gitignore")).toMatchInlineSnapshot(`"node_modules/"`);
     });
   });
 });

integration/__fixtures__/lerna-init/.gitignore

@@ -0,0 +1 @@
+dist/

integration/lerna-init.test.js

@@ -19,6 +19,7 @@ describe("lerna init", () => {
     expect(stderr).toMatchInlineSnapshot(`
       lerna notice cli __TEST_VERSION__
       lerna info Initializing Git repository
+      lerna info Creating .gitignore
       lerna info Creating package.json
       lerna info Creating lerna.json
       lerna info Creating packages directory