fix: preserve trailing whitespace in manifest

lib/createInlinePluginCreator.js

@@ -1,8 +1,9 @@
 const { writeFileSync } = require("fs");
 const debug = require("debug")("msr:inlinePlugin");
 const getCommitsFiltered = require("./getCommitsFiltered");
-const { getManifest, getIndent } = require("./getManifest");
+const getManifest = require("./getManifest");
 const hasChangedDeep = require("./hasChangedDeep");
+const recognizeFormat = require("./recognizeFormat");
 const { get } = require("lodash");
 
 /**
@@ -32,7 +33,7 @@ function createInlinePluginCreator(packages, multiContext, synchronizer, flags)
 	const updateManifestDeps = (pkg, path) => {
 		// Get and parse manifest file contents.
 		const manifest = getManifest(path);
-		const indent = getIndent(path);
+		const { indent, trailingWhitespace } = recognizeFormat(manifest.__contents__);
 		const updateDependency = (scope, name, version) => {
 			if (get(manifest, `${scope}.${name}`)) {
 				manifest[scope][name] = version;
@@ -56,7 +57,7 @@ function createInlinePluginCreator(packages, multiContext, synchronizer, flags)
 		});
 
 		// Write package.json back out.
-		writeFileSync(path, JSON.stringify(manifest, null, indent));
+		writeFileSync(path, JSON.stringify(manifest, null, indent) + trailingWhitespace);
 	};
 
 	/**

lib/getManifest.js

@@ -17,7 +17,7 @@ function readManifest(path) {
 	try {
 		stat = lstatSync(path);
 	} catch (_) {
-		// istanbul ignore next (hard to test — happens if no read acccess etc).
+		// istanbul ignore next (hard to test — happens if no read access etc).
 		throw new ReferenceError(`package.json cannot be read: "${path}"`);
 	}
 
@@ -33,22 +33,6 @@ function readManifest(path) {
 	}
 }
 
-/**
- * Extract the current indent sequence from file.
- *
- * @param {string} path The path to the package.json manifest file.
- * @returns {string} indent symbols
- *
- * @internal
- */
-function getIndent(path) {
-	// Read the file.
-	const contents = readManifest(path);
-	const match = /\n([^"]+)/.exec(contents);
-
-	return match ? match[1] : 2;
-}
-
 /**
  * Get the parsed contents of a package.json manifest file.
  *
@@ -87,9 +71,12 @@ function getManifest(path) {
 	checkDeps("peerDependencies");
 	checkDeps("optionalDependencies");
 
+	// NOTE non-enumerable prop is skipped by JSON.stringify
+	Object.defineProperty(manifest, "__contents__", { enumerable: false, value: contents });
+
 	// Return contents.
 	return manifest;
 }
 
 // Exports.
-module.exports = { getManifest, getIndent };
+module.exports = getManifest;

lib/getWorkspacesYarn.js

@@ -1,5 +1,5 @@
 const glob = require("bash-glob");
-const { getManifest } = require("./getManifest");
+const getManifest = require("./getManifest");
 const { checker } = require("./blork");
 
 /**

lib/multiSemanticRelease.js

@@ -6,7 +6,7 @@ const getLogger = require("./getLogger");
 const getSynchronizer = require("./getSynchronizer");
 const getConfig = require("./getConfig");
 const getConfigSemantic = require("./getConfigSemantic");
-const { getManifest } = require("./getManifest");
+const getManifest = require("./getManifest");
 const cleanPath = require("./cleanPath");
 const RescopedStream = require("./RescopedStream");
 const createInlinePluginCreator = require("./createInlinePluginCreator");

lib/recognizeFormat.js

@@ -0,0 +1,25 @@
+/**
+ * Information about the format of a file.
+ * @typedef FileFormat
+ * @property {string|number} indent Indentation characters
+ * @property {string} trailingWhitespace Trailing whitespace at the end of the file
+ */
+
+/**
+ * Detects the indentation and trailing whitespace of a file.
+ *
+ * @param {string} contents contents of the file
+ * @returns {FileFormat} Formatting of the file
+ */
+function recognizeFormat(contents) {
+	const indentMatch = /\n([^"]+)/.exec(contents);
+	const trailingWhitespaceMatch = /}(\s*)$/.exec(contents);
+
+	return {
+		indent: indentMatch ? indentMatch[1] : 2,
+		trailingWhitespace: trailingWhitespaceMatch ? trailingWhitespaceMatch[1] : "",
+	};
+}
+
+// Exports.
+module.exports = recognizeFormat;

test/lib/recognizeFormat.test.js

@@ -0,0 +1,24 @@
+/** @typedef {import('@types/jest')} */
+const recognizeFormat = require("../../lib/recognizeFormat");
+
+// Tests.
+describe("recognizeFormat()", () => {
+	describe("Indentation", () => {
+		test("Normal indentation", () =>
+			expect(
+				recognizeFormat(`{
+	"a": "b",
+	"c": {
+		"d": "e"
+	}
+}`).indent
+			).toBe("\t"));
+		test("No indentation", () => expect(recognizeFormat('{"a": "b"}').indent).toBe(2));
+	});
+
+	describe("Trailing whitespace", () => {
+		test("No trailing whitespace", () => expect(recognizeFormat('{"a": "b"}').trailingWhitespace).toBe(""));
+		test("Newline", () => expect(recognizeFormat('{"a": "b"}\n').trailingWhitespace).toBe("\n"));
+		test("Multiple newlines", () => expect(recognizeFormat('{"a": "b"}\n\n').trailingWhitespace).toBe("\n\n"));
+	});
+});