[experimental] Add linting step in test pipeline (#1172)

* Add eslint as dev dep, reorder scripts.

* Add tests & docs to eslintignore.

* Add eslintcache to gitignore.

* Update yarn lock file 😽.

* Add linting step in the test pipeline.

* Add a set of really basic rules for linting.

* Fix linting 🚀.

* No need for .jsx files to be linted...

* Reorder rules alphabetically.

* Refine rules: drop styling ones, only keep what provides dead code elimination.

* Add no-console rule to be consistent along with the no-debugger one.

* Remove empty line.

* Add eslint-disable-next-line no-console where console log/warn/error are allowed.

* Drop no-console rule.

* Remove eslint-disable-next-line no-console comments.

* Remove linting step in Travis CI.

* Fix linting after merging current master.

* Run `npm test -- -u` after noticing one test was out of sync.

* Drop eslint references from previous implementation.

* Revert yarn lock file.

* Revert scripts ordering.

* Fix incorrect yarn lock file.

src/comments.js

@@ -6,12 +6,10 @@ var n = types.namedTypes;
 var isArray = types.builtInTypes.array;
 var isObject = types.builtInTypes.object;
 var docBuilders = require("./doc-builders");
-var fromString = docBuilders.fromString;
 var concat = docBuilders.concat;
 var hardline = docBuilders.hardline;
 var breakParent = docBuilders.breakParent;
 var indent = docBuilders.indent;
-var align = docBuilders.align;
 var lineSuffix = docBuilders.lineSuffix;
 var join = docBuilders.join;
 var util = require("./util");
@@ -126,7 +124,7 @@ function decorateComment(node, comment, text) {
   }
 }
 
-function attach(comments, ast, text, options) {
+function attach(comments, ast, text) {
   if (!isArray.check(comments)) {
     return;
   }
@@ -810,7 +808,6 @@ function getQuasiRange(expr) {
 function printLeadingComment(commentPath, print, options) {
   const comment = commentPath.getValue();
   const contents = printComment(commentPath);
-  const text = options.originalText;
   const isBlock = comment.type === "Block" || comment.type === "CommentBlock";
 
   // Leading block comments should see if they need to stay on the
@@ -825,7 +822,7 @@ function printLeadingComment(commentPath, print, options) {
   return concat([contents, hardline]);
 }
 
-function printTrailingComment(commentPath, print, options, parentNode) {
+function printTrailingComment(commentPath, print, options) {
   const comment = commentPath.getValue();
   const contents = printComment(commentPath);
   const isBlock = comment.type === "Block" || comment.type === "CommentBlock";
@@ -864,7 +861,6 @@ function printTrailingComment(commentPath, print, options, parentNode) {
 }
 
 function printDanglingComments(path, options, sameIndent) {
-  const text = options.originalText;
   const parts = [];
   const node = path.getValue();
 

src/doc-builders.js

@@ -1,8 +1,5 @@
 "use strict";
 
-const utils = require("./doc-utils");
-const willBreak = utils.willBreak;
-
 function assertDoc(val) {
   if (
     !(typeof val === "string" || (val != null && typeof val.type === "string"))

src/fast-path.js

@@ -4,7 +4,6 @@ var assert = require("assert");
 var types = require("ast-types");
 var util = require("./util");
 var n = types.namedTypes;
-var Node = n.Node;
 var isArray = types.builtInTypes.array;
 var isNumber = types.builtInTypes.number;
 
@@ -181,7 +180,7 @@ FPp.map = function map(callback /*, name1, name2, ... */) {
 
 // Inspired by require("ast-types").NodePath.prototype.needsParens, but
 // more efficient because we're iterating backwards through a stack.
-FPp.needsParens = function(assumeExpressionContext) {
+FPp.needsParens = function() {
   var parent = this.getParentNode();
   if (!parent) {
     return false;
@@ -536,10 +535,6 @@ FPp.needsParens = function(assumeExpressionContext) {
   return false;
 };
 
-function isBinary(node) {
-  return n.BinaryExpression.check(node) || n.LogicalExpression.check(node);
-}
-
 function containsCallExpression(node) {
   if (n.CallExpression.check(node)) {
     return true;

src/printer.js

@@ -29,7 +29,6 @@ var isEmpty = docUtils.isEmpty;
 var types = require("ast-types");
 var namedTypes = types.namedTypes;
 var isString = types.builtInTypes.string;
-var isObject = types.builtInTypes.object;
 
 function shouldPrintComma(options, level) {
   level = level || "es5";
@@ -307,10 +306,10 @@ function genericPrintNoParens(path, options, print, args) {
       return join(".", n.body);
     case "Identifier":
       var parentNode = path.getParentNode()
-      var isFunctionDeclarationIdentifier = 
+      var isFunctionDeclarationIdentifier =
         parentNode.type === 'DeclareFunction' &&
         parentNode.id === n
-          
+
       return concat([
         n.name,
         n.optional ? "?" : "",
@@ -1930,7 +1929,7 @@ function genericPrintNoParens(path, options, print, args) {
       return concat(parts);
     case "TSTypeReference":
       parts.push(path.call(print, "typeName"))
-      
+
       if (n.typeArguments) {
         parts.push(
           "<",
@@ -1938,7 +1937,7 @@ function genericPrintNoParens(path, options, print, args) {
           ">"
         )
       }
-      
+
       return concat(parts);
     case "TSCallSignature":
       return concat([
@@ -2013,14 +2012,14 @@ function genericPrintNoParens(path, options, print, args) {
       ])
     case "TSTypeParameter":
       parts.push(path.call(print, "name"))
-      
+
       if (n.constraint) {
         parts.push(
           " in ",
           path.call(print, "constraint")
         )
       }
-      
+
       return concat(parts)
     // TODO
     case "ClassHeritage":
@@ -2061,7 +2060,6 @@ function genericPrintNoParens(path, options, print, args) {
     case "XMLComment":
     case "XMLProcessingInstruction":
     default:
-      debugger;
       throw new Error("unknown type: " + JSON.stringify(n.type));
   }
 }
@@ -2144,7 +2142,7 @@ function printPropertyKey(path, options, print) {
   ) {
     // 'a' -> a
     return path.call(
-      keyPath => comments.printComments(keyPath, p => key.value, options),
+      keyPath => comments.printComments(keyPath, () => key.value, options),
       "key"
     );
   }
@@ -2543,14 +2541,6 @@ function printReturnType(path, print) {
   return concat(parts);
 }
 
-function typeIsFunction(type) {
-  return (
-    type === "FunctionExpression" ||
-    type === "ArrowFunctionExpression" ||
-    type === "NewExpression"
-  );
-}
-
 function printExportDeclaration(path, options, print) {
   const decl = path.getValue();
   const semi = options.semi ? ";" : "";
@@ -2658,7 +2648,7 @@ function printFlowDeclaration(path, parts) {
   return concat(parts);
 }
 
-function getFlowVariance(path, options) {
+function getFlowVariance(path) {
   if (!path.variance) {
     return null;
   }
@@ -2760,7 +2750,7 @@ function printMemberChain(path, options, print) {
         node: node,
         printed: comments.printComments(
           path,
-          p => printArgumentsList(path, options, print),
+          () => printArgumentsList(path, options, print),
           options
         )
       });
@@ -2770,7 +2760,7 @@ function printMemberChain(path, options, print) {
         node: node,
         printed: comments.printComments(
           path,
-          p => printMemberLookup(path, options, print),
+          () => printMemberLookup(path, options, print),
           options
         )
       });
@@ -3190,7 +3180,7 @@ function printJSXElement(path, options, print) {
   ]);
 }
 
-function maybeWrapJSXElementInParens(path, elem, options) {
+function maybeWrapJSXElementInParens(path, elem) {
   const parent = path.getParentNode();
   if (!parent) return elem;
 
@@ -3295,7 +3285,7 @@ function printBinaryishExpressions(path, print, options, isNested, isInsideParen
     // the other ones since we don't call the normal print on BinaryExpression,
     // only for the left and right parts
     if (isNested && node.comments) {
-      parts = comments.printComments(path, p => concat(parts), options);
+      parts = comments.printComments(path, () => concat(parts), options);
     }
   } else {
     // Our stopping case. Simply print the node normally.
@@ -3347,24 +3337,6 @@ function adjustClause(node, clause, forceSpace) {
   return indent(concat([line, clause]));
 }
 
-function shouldTypeScriptTypeAvoidColon(path) {
-  // As the special TS nodes isn't returned by the node helpers,
-  // we use the stack directly to get the parent node.
-  const parent = path.stack[path.stack.length - 3];
-
-  switch (parent.type) {
-    case "TSFunctionType":
-    case "TSIndexSignature":
-    case "TSParenthesizedType":
-    case "TSCallSignature":
-    case "TSConstructSignature":
-    case "TSAsExpression":
-      return true;
-    default:
-      return false;
-  }
-}
-
 function nodeStr(node, options) {
   const str = node.value;
   isString.assert(str);
@@ -3460,13 +3432,6 @@ function printNumber(rawNumber) {
   );
 }
 
-function isFirstStatement(path) {
-  const parent = path.getParentNode();
-  const node = path.getValue();
-  const body = parent.body;
-  return body && body[0] === node;
-}
-
 function isLastStatement(path) {
   const parent = path.getParentNode();
   const node = path.getValue();
@@ -3568,7 +3533,6 @@ function classPropMayCauseASIProblems(path) {
 function classChildNeedsASIProtection(node) {
   if (!node) return;
 
-  let isAsync, isGenerator;
   switch (node.type) {
     case "ClassProperty":
       return node.computed;

src/util.js

@@ -1,8 +1,5 @@
 "use strict";
 
-var types = require("ast-types");
-var n = types.namedTypes;
-
 function isExportDeclaration(node) {
   if (node)
     switch (node.type) {

tests/flow_function_parentheses/__snapshots__/jsfmt.spec.js.snap

@@ -168,7 +168,7 @@ type f = /* comment */ arg => void;
 
 type f = arg /* comment */ => void;
 
-type f = ?arg => void;
+type f = (?arg) => void;
 
 class X {
   constructor(

tests_config/run_spec.js

@@ -58,7 +58,6 @@ function run_spec(dirname, options, additionalParsers) {
       if (RUN_AST_TESTS) {
         const source = read(dirname + "/" + filename);
         const ast = removeEmptyStatements(parse(source));
-        let prettyprinted = false;
         let ppast;
         let pperr = null;
         try {