Support project as well as user .npmrc files.

See #89.

Checks for a project local `.npmrc` before the user `.npmrc`, which
avoids potentially misleading log messages (not finding a user `.npmrc`
is not a problem if there's a project one) and unecessarily generating
a user `.npmrc`.

Author: elyobo

README.md

@@ -104,13 +104,13 @@ jobs:
         run: my-slack-bot send-notification --message "A new version of ${GITHUB_REPOSITORY} was published!"
 ```
 
-By default the GitHub Action creates a `.npmrc` file with the following content:
+By default the GitHub Action creates a `.npmrc` file with the following content to the user `$HOME` `.npmrc`:
 
 ```
 //registry.npmjs.org/:_authToken=${process.env.NPM_TOKEN}
 ```
 
-However, if a `.npmrc` file is found, the GitHub Action does not recreate the file. This is useful if you need to configure the `.npmrc` file on your own.
+However, if either a project or user `.npmrc` file is found, the GitHub Action does not recreate the file. This is useful if you need to configure the `.npmrc` file on your own.
 For example, you can add a step before running the Changesets GitHub Action:
 
 ```yml

src/index.ts

@@ -67,29 +67,34 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
         "No changesets found. Attempting to publish any unpublished packages to npm"
       );
 
-      let userNpmrcPath = `${process.env.HOME}/.npmrc`;
-      if (await fileExists(userNpmrcPath)) {
-        core.info("Found existing user .npmrc file");
-        const userNpmrcContent = await fs.readFile(userNpmrcPath, "utf8");
+      let userNpmrcPath = `${process.env.HOME}/.npmrc`
+      let npmrcPath = await ["./.npmrc", userNpmrcPath]
+        .reduce<Promise<string | undefined>>(async (acc, path) => {
+          if (await acc) return acc;
+          return await fileExists(path) ? path : undefined;
+        }, Promise.resolve(undefined));
+      if (npmrcPath) {
+        core.info(`Found existing .npmrc file at "${npmrcPath}"`);
+        const userNpmrcContent = await fs.readFile(npmrcPath, "utf8");
         const authLine = userNpmrcContent.split("\n").find((line) => {
           // check based on https://github.com/npm/cli/blob/8f8f71e4dd5ee66b3b17888faad5a7bf6c657eed/test/lib/adduser.js#L103-L105
           return /^\s*\/\/registry\.npmjs\.org\/:[_-]authToken=/i.test(line);
         });
         if (authLine) {
           core.info(
-            "Found existing auth token for the npm registry in the user .npmrc file"
+            "Found existing auth token for the npm registry in the .npmrc file"
           );
         } else {
           core.info(
-            "Didn't find existing auth token for the npm registry in the user .npmrc file, creating one"
+            "Didn't find existing auth token for the npm registry in the .npmrc file, creating one"
           );
           await fs.appendFile(
-            userNpmrcPath,
+            npmrcPath,
             `\n//registry.npmjs.org/:_authToken=${process.env.NPM_TOKEN}\n`
           );
         }
       } else {
-        core.info("No user .npmrc file found, creating one");
+        core.info("No .npmrc file found, creating one");
         await fs.writeFile(
           userNpmrcPath,
           `//registry.npmjs.org/:_authToken=${process.env.NPM_TOKEN}\n`