Add eslint 6 support

.travis.yml

@@ -3,7 +3,6 @@ language: node_js
 node_js:
   - 10
   - 8
-  - 6
 
 env:
   - WEBPACK_VERSION=4

index.js

@@ -162,12 +162,19 @@ module.exports = function(input, map) {
 
   var userEslintPath = userOptions.eslintPath;
 
+  var eslintPkgPath = "eslint/package.json";
+  if (userEslintPath) {
+    eslintPkgPath = userEslintPath + "/package.json";
+  }
+
+  var eslintVersion = require(eslintPkgPath).version;
+
   var config = assign(
     // loader defaults
     {
       cacheIdentifier: JSON.stringify({
         "eslint-loader": pkg.version,
-        eslint: require(userEslintPath || "eslint").version
+        eslint: eslintVersion
       }),
       eslintPath: "eslint"
     },
@@ -188,17 +195,6 @@ module.exports = function(input, map) {
       // ignored
     }
   }
-  if (config.formatter == null || typeof config.formatter !== "function") {
-    if (userEslintPath) {
-      try {
-        config.formatter = require(userEslintPath + "/lib/formatters/stylish");
-      } catch (e) {
-        config.formatter = require("eslint/lib/formatters/stylish");
-      }
-    } else {
-      config.formatter = require("eslint/lib/formatters/stylish");
-    }
-  }
 
   var cacheDirectory = config.cache;
   var cacheIdentifier = config.cacheIdentifier;
@@ -207,11 +203,17 @@ module.exports = function(input, map) {
 
   // Create the engine only once per config
   var configHash = objectHash(config);
+
   if (!engines[configHash]) {
     var eslint = require(config.eslintPath);
     engines[configHash] = new eslint.CLIEngine(config);
   }
 
+  var engine = engines[configHash];
+  if (config.formatter == null || typeof config.formatter !== "function") {
+    config.formatter = engine.getFormatter("stylish");
+  }
+
   webpack.cacheable();
 
   var resourcePath = webpack.resourcePath;
@@ -223,7 +225,6 @@ module.exports = function(input, map) {
     resourcePath = resourcePath.substr(cwd.length + 1);
   }
 
-  var engine = engines[configHash];
   // return early if cached
   if (config.cache) {
     var callback = webpack.async();

package.json

@@ -16,7 +16,7 @@
     "index.js"
   ],
   "peerDependencies": {
-    "eslint": ">=1.6.0 <6.0.0",
+    "eslint": ">=1.6.0 <7.0.0",
     "webpack": ">=2.0.0 <5.0.0"
   },
   "dependencies": {
@@ -28,7 +28,7 @@
   },
   "devDependencies": {
     "ava": "^0.17.0",
-    "eslint": "^5.1.0",
+    "eslint": "^6.0.1",
     "eslint-config-i-am-meticulous": "^11.0.0",
     "eslint-friendly-formatter": "^2.0.4",
     "husky": "^0.14.3",

test/formatter-multiple-entries.js

@@ -3,13 +3,15 @@ var path = require("path");
 
 var test = require("ava");
 var webpack = require("webpack");
+var CLIEngine = require("eslint").CLIEngine;
 
 var conf = require("./utils/conf");
 
 test.cb(
   "eslint-loader can be configured to write multiple eslint result files",
   function(t) {
     var outputFilename = "outputReport-[name].txt";
+
     var config = conf(
       {
         entry: [
@@ -19,15 +21,15 @@ test.cb(
         ]
       },
       {
-        formatter: require("eslint/lib/formatters/checkstyle"),
+        formatter: CLIEngine.getFormatter("checkstyle"),
         outputReport: {
           filePath: outputFilename
         }
       }
     );
 
     /* Plan for the success count. Failure cases are going to fail anyway so the
-   * count being off for those cases doesn't matter. */
+     * count being off for those cases doesn't matter. */
     t.plan(config.entry.length * 2);
 
     webpack(config, function(err, stats) {

test/formatter-write.js

@@ -3,6 +3,7 @@ var fs = require("fs");
 
 var test = require("ava");
 var webpack = require("webpack");
+var CLIEngine = require("eslint").CLIEngine;
 
 var conf = require("./utils/conf");
 
@@ -17,7 +18,7 @@ test.cb(
         entry: "./test/fixtures/error.js"
       },
       {
-        formatter: require("eslint/lib/formatters/checkstyle"),
+        formatter: CLIEngine.getFormatter("checkstyle"),
         outputReport: {
           filePath: outputFilename
         }

test/mock/eslint/index.js

@@ -1,33 +1,56 @@
-function CLIEngine() {
-
-}
+function CLIEngine() {}
 
 CLIEngine.prototype.executeOnText = function() {
   return {
-    results: [{
-      filePath: "",
-      messages: [{
-        ruleId: "no-undef",
-        severity: 2,
-        message: "Fake error",
-        line: 1,
-        column: 11,
-        nodeType: "Identifier",
-        source: "var foo = stuff",
-      }],
-      errorCount: 2,
-      warningCount: 0,
-      fixableErrorCount: 0,
-      fixableWarningCount: 0,
-      source: "",
-    }],
+    results: [
+      {
+        filePath: "",
+        messages: [
+          {
+            ruleId: "no-undef",
+            severity: 2,
+            message: "Fake error",
+            line: 1,
+            column: 11,
+            nodeType: "Identifier",
+            source: "var foo = stuff"
+          }
+        ],
+        errorCount: 2,
+        warningCount: 0,
+        fixableErrorCount: 0,
+        fixableWarningCount: 0,
+        source: ""
+      }
+    ],
     errorCount: 2,
     warningCount: 0,
     fixableErrorCount: 0,
-    fixableWarningCount: 0,
+    fixableWarningCount: 0
+  };
+};
+
+CLIEngine.prototype.getFormatter = function(format) {
+  const resolvedFormatName = format || "stylish";
+
+  if (typeof resolvedFormatName !== "string") {
+    return null;
+  }
+
+  const eslintVersion = require("./package.json").version;
+  const formatterPath =
+    eslintVersion >= "6.0.0"
+      ? "./lib/cli-engine/formatters/stylish"
+      : "./lib/formatters/stylish";
+
+  try {
+    return require(formatterPath);
+  } catch (ex) {
+    ex.message = `There was a problem loading formatter: ${formatterPath}\nError: ${ex.message}`;
+    throw ex;
   }
-}
+};
 
 module.exports = {
-  CLIEngine: CLIEngine,
-}
+  CLIEngine: CLIEngine
+};

test/mock/eslint/lib/cli-engine/formatters/stylish.js

@@ -0,0 +1,3 @@
+module.exports = function(result) {
+  return JSON.stringify(result);
+};

test/mock/eslint/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "eslint",
+  "version": "5.16.0"
+}