fix(publish): Make the missing license warning clearer and more actio…

…nable (#1921)

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

@@ -11,6 +11,7 @@ jest.mock("../../version/lib/is-anything-committed");
 jest.mock("../../version/lib/is-behind-upstream");
 jest.mock("../../version/lib/remote-branch-exists");
 
+const fs = require("fs-extra");
 const path = require("path");
 
 // mocked modules
@@ -70,9 +71,37 @@ describe("licenses", () => {
     await lernaPublish(cwd)();
 
     const [warning] = loggingOutput("warn");
-    expect(warning).toMatch("Packages package-1, package-3 are missing a license");
+    expect(warning).toMatchInlineSnapshot(`
+"Packages package-1 and package-3 are missing a license.
+One way to fix this is to add a LICENSE.md file to the root of this repository.
+See https://choosealicense.com for additional guidance."
+`);
 
     expect(createTempLicenses).toHaveBeenLastCalledWith(undefined, []);
     expect(removeTempLicenses).toHaveBeenLastCalledWith([]);
   });
+
+  it("warns when one package needs a license", async () => {
+    const cwd = await initFixture("licenses");
+
+    // remove root license so warning is triggered
+    await fs.remove(path.join(cwd, "LICENSE"));
+
+    await lernaPublish(cwd)();
+
+    const [warning] = loggingOutput("warn");
+    expect(warning).toMatch("Package package-1 is missing a license.");
+  });
+
+  it("warns when multiple packages need a license", async () => {
+    const cwd = await initFixture("licenses-missing");
+
+    // simulate _all_ packages missing a license
+    await fs.remove(path.join(cwd, "packages/package-2/LICENSE"));
+
+    await lernaPublish(cwd)();
+
+    const [warning] = loggingOutput("warn");
+    expect(warning).toMatch("Packages package-1, package-2, and package-3 are missing a license.");
+  });
 });

commands/publish/index.js

@@ -378,9 +378,25 @@ class PublishCommand extends Command {
       .then(packagesWithoutLicense => {
         if (packagesWithoutLicense.length && !this.project.licensePath) {
           this.packagesToBeLicensed = [];
+
+          const names = packagesWithoutLicense.map(pkg => pkg.name);
+          const noun = names.length > 1 ? "Packages" : "Package";
+          const verb = names.length > 1 ? "are" : "is";
+          const list =
+            names.length > 1
+              ? `${names.slice(0, -1).join(", ")}${names.length > 2 ? "," : ""} and ${
+                  names[names.length - 1] /* oxford commas _are_ that important */
+                }`
+              : names[0];
+
           this.logger.warn(
             "ENOLICENSE",
-            `Packages ${packagesWithoutLicense.map(pkg => pkg.name).join(", ")} are missing a license`
+            "%s %s %s missing a license.\n%s\n%s",
+            noun,
+            list,
+            verb,
+            "One way to fix this is to add a LICENSE.md file to the root of this repository.",
+            "See https://choosealicense.com for additional guidance."
           );
         } else {
           this.packagesToBeLicensed = packagesWithoutLicense;