Fixed: ignore cache when eslint rules have changed (#151)

* Fixed: ignore cache when eslint rules have changed

* Update cache test with new test runner

Author: peternewnham

index.js

@@ -8,6 +8,7 @@ var objectHash = require("object-hash")
 var os = require("os")
 
 var engines = {}
+var rules = {}
 var cache = null
 var cachePath = null
 
@@ -29,25 +30,39 @@ function lint(input, config, webpack) {
     resourcePath = resourcePath.substr(cwd.length + 1)
   }
 
+  // get engine
+  var configHash = objectHash(config)
+  var engine = engines[configHash]
+  var rulesHash = rules[configHash]
+
   var res
   // If cache is enable and the data are the same as in the cache, just
   // use them
   if (config.cache) {
+    // just get rules hash once per engine for performance reasons
+    if (!rulesHash) {
+      rulesHash = objectHash(engine.getConfigForFile(resourcePath))
+      rules[configHash] = rulesHash
+    }
     var inputMD5 = crypto.createHash("md5").update(input).digest("hex")
-    if (cache[resourcePath] && cache[resourcePath].hash === inputMD5) {
+    if (
+      cache[resourcePath] &&
+      cache[resourcePath].hash === inputMD5 &&
+      cache[resourcePath].rules === rulesHash
+    ) {
       res = cache[resourcePath].res
     }
   }
 
   // Re-lint the text if the cache off or miss
   if (!res) {
-    var configHash = objectHash(config)
-    res = engines[configHash].executeOnText(input, resourcePath, true)
+    res = engine.executeOnText(input, resourcePath, true)
 
     // Save new results in the cache
     if (config.cache) {
       cache[resourcePath] = {
         hash: inputMD5,
+        rules: rulesHash,
         res: res,
       }
       fs.writeFileSync(cachePath, JSON.stringify(cache))

test/cache.js

@@ -0,0 +1,48 @@
+var test = require("ava")
+var webpack = require("webpack")
+var conf = require("./utils/conf")
+var fs = require("fs")
+
+var cacheFilePath = "./node_modules/.cache/eslint-loader/data.json"
+
+test.cb("eslint-loader can cache results", function(t) {
+  t.plan(2)
+  webpack(conf(
+    {
+      entry: "./test/fixtures/cache.js",
+    },
+    {
+      cache: true,
+    }
+  ),
+  function(err) {
+    if (err) {
+      throw err
+    }
+
+    fs.readFile(cacheFilePath, "utf8", function(err, contents) {
+      if (err) {
+        t.fail("expected cache file to have been created")
+      }
+      else {
+        t.pass("cache file has been created")
+
+        var contentsJson = JSON.parse(contents)
+        t.deepEqual(
+          Object.keys(contentsJson["test/fixtures/cache.js"]),
+          ["hash", "rules", "res"],
+          "cache values have been set for the linted file"
+        )
+      }
+
+      t.end()
+
+    })
+
+  })
+})
+
+// delete the cache file once tests have completed
+test.after.always("teardown", function() {
+  fs.unlinkSync(cacheFilePath)
+})

test/fixtures/cache.js

@@ -0,0 +1,7 @@
+"use strict"
+
+function cacheIt() {
+  return "cache"
+}
+
+cacheIt()