test: replace function with arrow function and remove unused argument

test/parallel/test-readline-interface.js

@@ -277,7 +277,7 @@ function assertCursorRowsAndCols(rli, rows, cols) {
   const expectedLines = ['foo', 'bar', 'baz', 'bar', 'bat', 'bat'];
   // ['foo', 'baz', 'bar', bat'];
   let callCount = 0;
-  rli.on('line', function(line) {
+  rli.on('line', (line) => {
     assert.strictEqual(line, expectedLines[callCount]);
     callCount++;
   });
@@ -353,7 +353,7 @@ function assertCursorRowsAndCols(rli, rows, cols) {
   });
   const expectedLines = ['foo', 'bar', 'baz', 'bar', 'bat', 'bat'];
   let callCount = 0;
-  rli.on('line', function(line) {
+  rli.on('line', (line) => {
     assert.strictEqual(line, expectedLines[callCount]);
     callCount++;
   });
@@ -380,7 +380,7 @@ function assertCursorRowsAndCols(rli, rows, cols) {
   const [rli, fi] = getInterface({ terminal: true });
   const keys = [];
   const err = new Error('bad thing happened');
-  fi.on('keypress', function(key) {
+  fi.on('keypress', (key) => {
     keys.push(key);
     if (key === 'X') {
       throw err;
@@ -795,7 +795,7 @@ for (let i = 0; i < 12; i++) {
   assert.strictEqual(isWarned(process.stdout._events), false);
 }
 
-[true, false].forEach(function(terminal) {
+[true, false].forEach((terminal) => {
   // Disable history
   {
     const [rli, fi] = getInterface({ terminal, historySize: 0 });
@@ -890,7 +890,7 @@ for (let i = 0; i < 12; i++) {
     const buf = Buffer.from('☮', 'utf8');
     const [rli, fi] = getInterface({ terminal });
     let callCount = 0;
-    rli.on('line', function(line) {
+    rli.on('line', (line) => {
       callCount++;
       assert.strictEqual(line, buf.toString('utf8'));
     });
@@ -1004,7 +1004,7 @@ for (let i = 0; i < 12; i++) {
     rli.setPrompt('ddd> ');
     rli.prompt();
     rli.write("really shouldn't be seeing this");
-    rli.question('What do you think of node.js? ', function(answer) {
+    rli.question('What do you think of node.js? ', (answer) => {
       console.log('Thank you for your valuable feedback:', answer);
       rli.close();
     });
@@ -1056,7 +1056,7 @@ for (let i = 0; i < 12; i++) {
     const crlfDelay = 200;
     const [rli, fi] = getInterface({ terminal, crlfDelay });
     let callCount = 0;
-    rli.on('line', function(line) {
+    rli.on('line', () => {
       callCount++;
     });
     fi.emit('data', '\r');
@@ -1078,7 +1078,7 @@ for (let i = 0; i < 12; i++) {
     const delay = 200;
     const [rli, fi] = getInterface({ terminal, crlfDelay });
     let callCount = 0;
-    rli.on('line', function(line) {
+    rli.on('line', () => {
       callCount++;
     });
     fi.emit('data', '\r');