fix(publish): Exit early when publishing w/o commits (#1453)

Lerna will throw an error, when publishing the current project and
there are no commits at all. This change will check if there are
any commits before proceeding with the publish command.

- Refactor the fixtures as preparation for tests with/without commit
- Add check if any commits are present
- Add tests for this behaviour

Closes #773.

commands/publish/__tests__/get-current-branch.test.js

@@ -8,3 +8,13 @@ test("getCurrentBranch", async () => {
 
   expect(getCurrentBranch({ cwd })).toBe("master");
 });
+
+test("getCurrentBranch without commit", async () => {
+  const cwd = await initFixture("root-manifest-only", false);
+  expect.assertions(1);
+  try {
+    await getCurrentBranch({ cwd });
+  } catch (err) {
+    expect(err.message).toMatch(/Command failed: git rev-parse --abbrev-ref HEAD.*/);
+  }
+});

commands/publish/__tests__/is-anything-commited.test.js

@@ -0,0 +1,21 @@
+"use strict";
+
+const execa = require("execa");
+const initFixture = require("@lerna-test/init-fixture")(__dirname);
+const isAnythingCommited = require("../lib/is-anything-commited");
+
+test("isAnythingCommited", async () => {
+  const cwd = await initFixture("root-manifest-only");
+
+  expect(isAnythingCommited({ cwd })).toBe(true);
+});
+
+test("isAnythingCommited without and with a commit", async () => {
+  const cwd = await initFixture("root-manifest-only", false);
+
+  expect(isAnythingCommited({ cwd })).toBe(false);
+
+  await execa("git", ["commit", "--allow-empty", "-m", "change"], { cwd });
+
+  expect(isAnythingCommited({ cwd })).toBe(true);
+});

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

@@ -225,6 +225,19 @@ describe("PublishCommand", () => {
     });
   });
 
+  it("exists with an error when no commits are present", async () => {
+    expect.assertions(2);
+    const testDir = await initFixture("normal", false);
+    try {
+      await lernaPublish(testDir)();
+    } catch (err) {
+      expect(err.prefix).toBe("ENOCOMMIT");
+      expect(err.message).toBe(
+        "No commits in this repository. Please commit something before using publish."
+      );
+    }
+  });
+
   it("exits with an error when git HEAD is detached", async () => {
     const cwd = await initFixture("normal-no-inter-dependencies");
 

commands/publish/index.js

@@ -34,6 +34,7 @@ const gitPush = require("./lib/git-push");
 const gitTag = require("./lib/git-tag");
 const isBehindUpstream = require("./lib/is-behind-upstream");
 const isBreakingChange = require("./lib/is-breaking-change");
+const isAnythingCommited = require("./lib/is-anything-commited");
 
 module.exports = factory;
 
@@ -81,6 +82,13 @@ class PublishCommand extends Command {
 
     // git validation, if enabled, should happen before updates are calculated and versions picked
     if (this.gitEnabled) {
+      if (!isAnythingCommited(this.execOpts)) {
+        throw new ValidationError(
+          "ENOCOMMIT",
+          "No commits in this repository. Please commit something before using publish."
+        );
+      }
+
       this.currentBranch = getCurrentBranch(this.execOpts);
 
       if (this.currentBranch === "HEAD") {

commands/publish/lib/is-anything-commited.js

@@ -0,0 +1,16 @@
+"use strict";
+
+const log = require("npmlog");
+const childProcess = require("@lerna/child-process");
+
+module.exports = isAnythingCommited;
+
+function isAnythingCommited(opts) {
+  log.silly("isAnythingCommited");
+
+  const anyCommits = childProcess.execSync("git", ["rev-list", "--count", "--all", "--max-count=1"], opts);
+
+  log.verbose("isAnythingCommited", anyCommits);
+
+  return Boolean(parseInt(anyCommits, 10));
+}

helpers/init-fixture/index.js

@@ -11,13 +11,17 @@ module.exports = initFixture;
 function initFixture(startDir) {
   return (fixtureName, commitMessage = "Init commit") => {
     const cwd = tempy.directory();
+    let chain = Promise.resolve();
 
-    return Promise.resolve()
-      .then(() => process.chdir(cwd))
-      .then(() => copyFixture(cwd, fixtureName, startDir))
-      .then(() => gitInit(cwd, "."))
-      .then(() => gitAdd(cwd, "-A"))
-      .then(() => gitCommit(cwd, commitMessage))
-      .then(() => cwd);
+    chain = chain.then(() => process.chdir(cwd));
+    chain = chain.then(() => copyFixture(cwd, fixtureName, startDir));
+    chain = chain.then(() => gitInit(cwd, "."));
+
+    if (commitMessage) {
+      chain = chain.then(() => gitAdd(cwd, "-A"));
+      chain = chain.then(() => gitCommit(cwd, commitMessage));
+    }
+
+    return chain.then(() => cwd);
   };
 }