repl: don't accumulate excess indentation in .load

When using .load the REPL would accumulate indentation with each line
including the indentation from all previous lines. Now it keeps the
indentation at the correct level.

Fixes: #47673
PR-URL: #49461
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Kohei Ueno <kohei.ueno119@gmail.com>

lib/repl.js

@@ -204,6 +204,7 @@ const domainSet = new SafeWeakSet();
 
 const kBufferedCommandSymbol = Symbol('bufferedCommand');
 const kContextId = Symbol('contextId');
+const kLoadingSymbol = Symbol('loading');
 
 let addedNewListener = false;
 
@@ -882,7 +883,7 @@ function REPLServer(prompt,
       self[kBufferedCommandSymbol] += cmd + '\n';
 
       // code alignment
-      const matches = self._sawKeyPress ?
+      const matches = self._sawKeyPress && !self[kLoadingSymbol] ?
         RegExpPrototypeExec(/^\s+/, cmd) : null;
       if (matches) {
         const prefix = matches[0];
@@ -1801,8 +1802,10 @@ function defineDefaultCommands(repl) {
         const stats = fs.statSync(file);
         if (stats && stats.isFile()) {
           _turnOnEditorMode(this);
+          this[kLoadingSymbol] = true;
           const data = fs.readFileSync(file, 'utf8');
           this.write(data);
+          this[kLoadingSymbol] = false;
           _turnOffEditorMode(this);
           this.write('\n');
         } else {

test/parallel/test-repl-save-load.js

@@ -67,9 +67,14 @@ testMe.complete('inner.o', common.mustSucceed((data) => {
 // Clear the REPL.
 putIn.run(['.clear']);
 
+testMe._sawKeyPress = true;
 // Load the file back in.
 putIn.run([`.load ${saveFileName}`]);
 
+// Make sure loading doesn't insert extra indentation
+// https://github.com/nodejs/node/issues/47673
+assert.strictEqual(testMe.line, '');
+
 // Make sure that the REPL data is "correct".
 testMe.complete('inner.o', common.mustSucceed((data) => {
   assert.deepStrictEqual(data, works);