Add support for prettierIgnore key in package.json

changelog_unreleased/cli/12672.md

@@ -0,0 +1,37 @@
+#### Add support for `prettierIgnore` key in `package.json` (#12672 by @mataha)
+
+```json
+{
+  "name": "pretty-package",
+  "version": "0.0.1",
+  "prettier": {
+    "semi": true,
+    "singleQuote": true,
+    "trailingComma": "all"
+  },
+  "prettierIgnore": ["dirty-file.js", "another-dirty-file.js"]
+}
+```
+
+```console
+# stable
+$ ls -1 --color=never *.js
+another-dirty-file.js
+dirty-file.js
+yet-another-dirty-file.js
+$ prettier *.js --check
+[warn] another-dirty-file.js
+[warn] dirty-file.js
+[warn] yet-another-dirty-file.js
+[warn] Code style issues found in the above file(s). Forgot to run Prettier?
+
+
+# main
+$ ls -1 --color=never *.js
+another-dirty-file.js
+dirty-file.js
+yet-another-dirty-file.js
+$ prettier *.js --check
+[warn] yet-another-dirty-file.js
+[warn] Code style issues found in the above file(s). Forgot to run Prettier?
+```

docs/ignore.md

@@ -3,7 +3,7 @@ id: ignore
 title: Ignoring Code
 ---
 
-Use `.prettierignore` to ignore (i.e. not reformat) certain files and folders completely.
+Use `.prettierignore` or a `prettierIgnore` key to ignore (i.e. not reformat) certain files and folders completely.
 
 Use “prettier-ignore” comments to ignore parts of files.
 
@@ -47,6 +47,23 @@ if [`--with-node-modules` CLI option](cli.md#--with-node-modules) provided
 
 (See also the [`--ignore-path` CLI option](cli.md#--ignore-path).)
 
+## Ignoring Files: prettierIgnore key
+
+If Prettier fails to find a `.prettierignore` file and an alternate file is not specified via `--ignore-path`, a `prettierIgnore` key in package.json will be checked for files to ignore instead:
+
+```json
+{
+  "name": "pretty-package",
+  "version": "0.0.1",
+  "prettier": {
+    "semi": true,
+    "singleQuote": true,
+    "trailingComma": "all"
+  },
+  "prettierIgnore": ["dirty-file.js", "another-dirty-file.js"]
+}
+```
+
 ## JavaScript
 
 A JavaScript comment of `// prettier-ignore` will exclude the next node in the abstract syntax tree from formatting.

src/utils/ignore.js

@@ -2,9 +2,46 @@ import path from "node:path";
 import url from "node:url";
 import { isUrl, toPath } from "url-or-path";
 import ignoreModule from "ignore";
+import mockable from "../common/mockable.js";
 import readFile from "../utils/read-file.js";
 
+const { lilconfig } = mockable;
+
+const createExplorer = lilconfig("prettierignore", {
+  packageProp: "prettierIgnore",
+  searchPlaces: ["package.json"],
+  transform(result) {
+    if (!result?.config) {
+      return result;
+    }
+
+    const { config, filepath } = result;
+
+    if (
+      !(
+        Array.isArray(config) &&
+        config.every((entry) => typeof entry === "string")
+      )
+    ) {
+      if (typeof config === "string") {
+        result.config = [config];
+      } else {
+        throw new TypeError(
+          "File list is only allowed to be an array of strings, " +
+            `but received ${typeof config} in "${filepath}"`,
+        );
+      }
+    }
+
+    return result;
+  },
+});
+
 const createIgnore = ignoreModule.default;
+
+/** @type {(file: string | URL) => Promise<import('lilconfig').LilconfigResult>} */
+const search = (file) => createExplorer.search(toResolvedPath(file));
+
 /** @type {(filePath: string) => string} */
 const slash =
   path.sep === "\\"
@@ -13,15 +50,23 @@ const slash =
 
 /**
  * @param {string | URL} file
- * @param {string | URL | undefined} ignoreFile
  * @returns {string}
  */
-function getRelativePath(file, ignoreFile) {
-  const ignoreFilePath = toPath(ignoreFile);
-  const filePath = isUrl(file)
+function toResolvedPath(file) {
+  return isUrl(file)
     ? url.fileURLToPath(file)
     : // @ts-expect-error -- URLs handled by `isUrl`
       path.resolve(file);
+}
+
+/**
+ * @param {string | URL} file
+ * @param {string | URL | undefined} ignoreFile
+ * @returns {string}
+ */
+function getRelativePath(file, ignoreFile) {
+  const filePath = toResolvedPath(file);
+  const ignoreFilePath = toPath(ignoreFile);
 
   return path.relative(
     // If there's an ignore-path set, the filename must be relative to the
@@ -34,7 +79,7 @@ function getRelativePath(file, ignoreFile) {
 /**
  * @param {string | URL | undefined} ignoreFile
  * @param {boolean} [withNodeModules]
- * @returns {Promise<(file: string | URL) => boolean>}
+ * @returns {Promise<(file: string | URL) => Promise<boolean>>}
  */
 async function createSingleIsIgnoredFunction(ignoreFile, withNodeModules) {
   let content = "";
@@ -47,13 +92,10 @@ async function createSingleIsIgnoredFunction(ignoreFile, withNodeModules) {
     content += "\n" + "node_modules";
   }
 
-  if (!content) {
-    return;
-  }
-
-  const ignore = createIgnore({ allowRelativePaths: true }).add(content);
-
-  return (file) => ignore.ignores(slash(getRelativePath(file, ignoreFile)));
+  return async (file) =>
+    createIgnore({ allowRelativePaths: true })
+      .add(content || (await search(file)).config)
+      .ignores(slash(getRelativePath(file, ignoreFile)));
 }
 
 /**

tests/integration/__tests__/__snapshots__/ignore-package-json.js.snap

@@ -0,0 +1,7 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`ignore file when using --debug-check (write) 1`] = `Array []`;
+
+exports[`outputs files as-is if no --write (write) 1`] = `Array []`;
+
+exports[`support prettierIgnore key in package.json (write) 1`] = `Array []`;

tests/integration/__tests__/ignore-package-json.js

@@ -0,0 +1,25 @@
+describe("support prettierIgnore key in package.json", () => {
+  runCli("cli/ignore-package-json", ["**/*.js", "-l"]).test({
+    status: 1,
+    stdout: "not-ignored.js\n",
+    stderr: "",
+  });
+});
+
+describe("ignore file when using --debug-check", () => {
+  runCli("cli/ignore-package-json", ["**/*.js", "--debug-check"]).test({
+    status: 0,
+    stdout: "not-ignored.js\n",
+    stderr: "",
+  });
+});
+
+describe("outputs files as-is if no --write", () => {
+  runCli("cli/ignore-package-json", ["ignored.js"], {
+    ignoreLineEndings: true,
+  }).test({
+    status: 0,
+    stdout: "'use strict';\n",
+    stderr: "",
+  });
+});

tests/integration/cli/ignore-package-json/ignored.js

@@ -0,0 +1 @@
+'use strict';

tests/integration/cli/ignore-package-json/not-ignored.js

@@ -0,0 +1 @@
+'use strict';

tests/integration/cli/ignore-package-json/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "ignore-package",
+  "version": "0.0.1",
+  "private": true,
+  "prettierIgnore": ["ignored.js"]
+}

tests/integration/cli/ignore-path/other-regular-modules.js

@@ -0,0 +1 @@
+'use strict';