tools: enable additional eslint rules

Enable additional rules that node either already adheres to
or it makes sense to do so going forward: for-direction,
accessor-pairs, no-lonely-if and symbol-description.

Fix all instances of no-lonely-if in lib & test and disable
accessor-pairs in test-util-inspect.

PR-URL: https://github.com/nodejs/node/pull/16243
Refs: https://eslint.org/docs/rules/for-direction
Refs: https://eslint.org/docs/rules/accessor-pairs
Refs: https://eslint.org/docs/rules/no-lonely-if
Refs: https://eslint.org/docs/rules/symbol-description
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

.eslintrc.yaml

@@ -18,6 +18,7 @@ overrides:
 rules:
   # Possible Errors
   # http://eslint.org/docs/rules/#possible-errors
+  for-direction: error
   no-control-regex: error
   no-debugger: error
   no-dupe-args: error
@@ -41,6 +42,7 @@ rules:
 
   # Best Practices
   # http://eslint.org/docs/rules/#best-practices
+  accessor-pairs: error
   dot-location: [error, property]
   eqeqeq: [error, smart]
   no-fallthrough: error
@@ -122,6 +124,7 @@ rules:
                 ignoreUrls: true,
                 tabWidth: 2}]
   new-parens: error
+  no-lonely-if: error
   no-mixed-spaces-and-tabs: error
   no-multiple-empty-lines: [error, {max: 2, maxEOF: 0, maxBOF: 0}]
   no-restricted-syntax: [error, {
@@ -172,6 +175,7 @@ rules:
   no-this-before-super: error
   prefer-const: [error, {ignoreReadBeforeAssign: true}]
   rest-spread-spacing: error
+  symbol-description: error
   template-curly-spacing: error
 
   # Custom rules in tools/eslint-rules

doc/.eslintrc.yaml

@@ -6,6 +6,7 @@ rules:
   no-undef: off
   no-unused-vars: off
   strict: off
+  symbol-description: off
 
   # add new ECMAScript features gradually
   no-var: error

lib/_http_incoming.js

@@ -301,9 +301,8 @@ function _addHeaderLine(field, value, dest) {
     } else {
       dest['set-cookie'] = [value];
     }
-  } else {
+  } else if (dest[field] === undefined) {
     // Drop duplicates
-    if (dest[field] === undefined)
     dest[field] = value;
   }
 }

lib/_http_outgoing.js

@@ -404,8 +404,7 @@ function _storeHeader(firstLine, headers) {
       this.chunkedEncoding = false;
     } else if (!this.useChunkedEncodingByDefault) {
       this._last = true;
-    } else {
-      if (!state.trailer &&
+    } else if (!state.trailer &&
                !this._removedContLen &&
                typeof this._contentLength === 'number') {
       state.header += 'Content-Length: ' + this._contentLength + CRLF;
@@ -419,7 +418,6 @@ function _storeHeader(firstLine, headers) {
       debug('Both Content-Length and Transfer-Encoding are removed');
     }
   }
-  }
 
   // Test non-chunked message does not have trailer header set,
   // message will be terminated by the first empty line after the

lib/_http_server.js

@@ -433,8 +433,8 @@ function socketOnEnd(server, socket, parser, state) {
     state.outgoing[state.outgoing.length - 1]._last = true;
   } else if (socket._httpMessage) {
     socket._httpMessage._last = true;
-  } else {
-    if (socket.writable) socket.end();
+  } else if (socket.writable) {
+    socket.end();
   }
 }
 
@@ -602,14 +602,12 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
         res.writeContinue();
         server.emit('request', req, res);
       }
-    } else {
-      if (server.listenerCount('checkExpectation') > 0) {
+    } else if (server.listenerCount('checkExpectation') > 0) {
       server.emit('checkExpectation', req, res);
     } else {
       res.writeHead(417);
       res.end();
     }
-    }
   } else {
     server.emit('request', req, res);
   }

lib/_stream_readable.js

@@ -40,9 +40,9 @@ const kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];
 function prependListener(emitter, event, fn) {
   // Sadly this is not cacheable as some libraries bundle their own
   // event emitter implementation with them.
-  if (typeof emitter.prependListener === 'function') {
+  if (typeof emitter.prependListener === 'function')
     return emitter.prependListener(event, fn);
-  } else {
+
   // This is a hack to make sure that our error handler is attached before any
   // userland ones.  NEVER DO THIS. This is here only because this code needs
   // to continue to work with older versions of Node.js that do not include
@@ -54,7 +54,6 @@ function prependListener(emitter, event, fn) {
   else
     emitter._events[event] = [fn, emitter._events[event]];
 }
-}
 
 function ReadableState(options, stream) {
   options = options || {};

lib/_tls_legacy.js

@@ -878,8 +878,8 @@ SecurePair.prototype.error = function(returnOnly) {
              /peer did not return a certificate/.test(err.message)) {
     // Not really an error.
     this.destroy();
-  } else {
-    if (!returnOnly) this.cleartext.emit('error', err);
+  } else if (!returnOnly) {
+    this.cleartext.emit('error', err);
   }
   return err;
 };

lib/child_process.js

@@ -324,10 +324,9 @@ exports.execFile = function(file /*, args, options, callback*/) {
       if (stdoutLen > options.maxBuffer) {
         ex = new Error('stdout maxBuffer exceeded');
         kill();
-      } else {
-        if (encoding)
+      } else if (encoding) {
         _stdout += chunk;
-        else
+      } else {
         _stdout.push(chunk);
       }
     });
@@ -343,10 +342,9 @@ exports.execFile = function(file /*, args, options, callback*/) {
       if (stderrLen > options.maxBuffer) {
         ex = new Error('stderr maxBuffer exceeded');
         kill();
-      } else {
-        if (encoding)
+      } else if (encoding) {
         _stderr += chunk;
-        else
+      } else {
         _stderr.push(chunk);
       }
     });

lib/events.js

@@ -280,14 +280,12 @@ function _addListener(target, type, listener, prepend) {
       // Adding the second element, need to change to array.
       existing = events[type] =
         prepend ? [listener, existing] : [existing, listener];
-    } else {
       // If we've already got an array, just append.
-      if (prepend) {
+    } else if (prepend) {
       existing.unshift(listener);
     } else {
       existing.push(listener);
     }
-    }
 
     // Check for listener leak
     if (!existing.warned) {

lib/fs.js

@@ -1262,8 +1262,7 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
           callback(writeErr);
         });
       }
-    } else {
-      if (written === length) {
+    } else if (written === length) {
       if (isUserFd) {
         callback(null);
       } else {
@@ -1277,7 +1276,6 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
       }
       writeAll(fd, isUserFd, buffer, offset, length, position, callback);
     }
-    }
   });
 }
 

lib/internal/http2/core.js

@@ -187,13 +187,12 @@ function onSessionHeaders(id, cat, flags, headers) {
       }
     } else if (cat === NGHTTP2_HCAT_PUSH_RESPONSE) {
       event = 'push';
-    } else {  // cat === NGHTTP2_HCAT_HEADERS:
-      if (!endOfStream && status !== undefined && status >= 200) {
+      // cat === NGHTTP2_HCAT_HEADERS:
+    } else if (!endOfStream && status !== undefined && status >= 200) {
       event = 'response';
     } else {
       event = endOfStream ? 'trailers' : 'headers';
     }
-    }
     debug(`[${sessionName(owner[kType])}] emitting stream '${event}' event`);
     process.nextTick(emit, stream, event, obj, flags, headers);
   }

lib/path.js

@@ -455,8 +455,7 @@ const win32 = {
       } else {
         return '';
       }
-    } else {
-      if (isAbsolute) {
+    } else if (isAbsolute) {
       if (tail.length > 0)
         return device + '\\' + tail;
       else
@@ -466,7 +465,6 @@ const win32 = {
     } else {
       return device;
     }
-    }
   },
 
 

lib/querystring.js

@@ -315,8 +315,7 @@ function parse(qs, sep, eq, options) {
             sepIdx = eqIdx = 0;
             continue;
           }
-        } else {
-          if (lastPos < end)
+        } else if (lastPos < end) {
           value += qs.slice(lastPos, end);
         }
 

lib/url.js

@@ -128,8 +128,7 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
       if (isWs)
         continue;
       lastPos = start = i;
-    } else {
-      if (inWs) {
+    } else if (inWs) {
       if (!isWs) {
         end = -1;
         inWs = false;
@@ -138,7 +137,6 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
       end = i;
       inWs = true;
     }
-    }
 
     // Only convert backslashes while we haven't seen a split character
     if (!split) {

test/.eslintrc.yaml

@@ -5,6 +5,7 @@ rules:
   # http://eslint.org/docs/rules/#ecmascript-6
   no-var: error
   prefer-const: error
+  symbol-description: off
 
   # Custom rules in tools/eslint-rules
   prefer-assert-iferror: error

test/abort/test-abort-uncaught-exception.js

@@ -24,10 +24,9 @@ function run(flags, signals) {
         assert.strictEqual(code, 0xC0000005);
       else
         assert.strictEqual(code, 1);
-    } else {
-      if (signals)
+    } else if (signals) {
       assert(signals.includes(sig), `Unexpected signal ${sig}`);
-      else
+    } else {
       assert.strictEqual(sig, null);
     }
   }));

test/parallel/test-cluster-disconnect-unshared-tcp.js

@@ -37,10 +37,8 @@ if (cluster.isMaster) {
     unbound.disconnect();
     unbound.on('disconnect', cluster.disconnect);
   }
-} else {
-  if (process.env.BOUND === 'y') {
+} else if (process.env.BOUND === 'y') {
   const source = net.createServer();
 
   source.listen(0);
 }
-}

test/parallel/test-cluster-disconnect-unshared-udp.js

@@ -40,10 +40,8 @@ if (cluster.isMaster) {
     unbound.disconnect();
     unbound.on('disconnect', cluster.disconnect);
   }
-} else {
-  if (process.env.BOUND === 'y') {
+} else if (process.env.BOUND === 'y') {
   const source = dgram.createSocket('udp4');
 
   source.bind(0);
 }
-}

test/parallel/test-cluster-worker-destroy.js

@@ -41,8 +41,7 @@ if (cluster.isMaster) {
     worker.on('disconnect', common.mustCall());
     worker.on('exit', common.mustCall());
   });
-} else {
-  if (cluster.worker.id === 1) {
+} else if (cluster.worker.id === 1) {
   // Call destroy when worker is disconnected
   cluster.worker.process.on('disconnect', function() {
     cluster.worker.destroy();
@@ -54,4 +53,3 @@ if (cluster.isMaster) {
   // Call destroy when worker is not disconnected yet
   cluster.worker.destroy();
 }
-}

test/parallel/test-tls-server-verify.js

@@ -335,8 +335,7 @@ function runTest(port, testIndex) {
     port = server.address().port;
     if (tcase.debug) {
       console.error(`${prefix}TLS server running on port ${port}`);
-    } else {
-      if (tcase.renegotiate) {
+    } else if (tcase.renegotiate) {
       runNextClient(0);
     } else {
       let clientsCompleted = 0;
@@ -351,7 +350,6 @@ function runTest(port, testIndex) {
         });
       }
     }
-    }
   });
 }
 

test/parallel/test-util-inspect.js

@@ -26,6 +26,8 @@ const JSStream = process.binding('js_stream').JSStream;
 const util = require('util');
 const vm = require('vm');
 
+/* eslint-disable accessor-pairs */
+
 assert.strictEqual(util.inspect(1), '1');
 assert.strictEqual(util.inspect(false), 'false');
 assert.strictEqual(util.inspect(''), "''");
@@ -1149,3 +1151,4 @@ if (typeof Symbol !== 'undefined') {
 }
 
 assert.doesNotThrow(() => util.inspect(process));
+/* eslint-enable accessor-pairs */

tools/eslint-rules/rules-utils.js

@@ -43,12 +43,10 @@ module.exports.inSkipBlock = function(node) {
         }
         return false;
       });
-    } else {
-      if (hasSkip(consequent.expression)) {
+    } else if (hasSkip(consequent.expression)) {
       hasSkipBlock = true;
     }
   }
-  }
   return hasSkipBlock;
 };