Fix: Exclude eol-last from output (fixes #48)

README.md

@@ -69,6 +69,12 @@ Blocks that don't specify either `js`, `javascript`, `jsx`, or `node` syntax are
     print("This doesn't get linted either.")
     ```
 
+## Unsatisfiable Rules
+
+Since code blocks are not files themselves but embedded inside a Markdown document, some rules do not apply to Markdown code blocks, and messages from these rules are automatically suppressed:
+
+- `eol-last`
+
 ## Contributing
 
 ```sh

lib/processor.js

@@ -12,6 +12,9 @@ var assign = require("object-assign");
 var remark = require("remark");
 
 var SUPPORTED_SYNTAXES = ["js", "javascript", "node", "jsx"];
+var UNSATISFIABLE_RULES = [
+    "eol-last" // The Markdown parser strips trailing newlines in code fences
+];
 
 var blocks = [];
 
@@ -57,6 +60,15 @@ function preprocess(text) {
     });
 }
 
+/**
+ * Excludes unsatisfiable rules from the list of messages.
+ * @param {Message} message A message from the linter.
+ * @returns {boolean} True if the message should be included in output.
+ */
+function excludeUnsatisfiableRules(message) {
+    return UNSATISFIABLE_RULES.indexOf(message.ruleId) < 0;
+}
+
 /**
  * Transforms generated messages for output.
  * @param {Array<Message[]>} messages An array containing one array of messages
@@ -65,7 +77,7 @@ function preprocess(text) {
  */
 function postprocess(messages) {
     return [].concat.apply([], messages.map(function(group, i) {
-        return group.map(function(message) {
+        return group.filter(excludeUnsatisfiableRules).map(function(message) {
             return assign({}, message, {
                 line: message.line + blocks[i].position.start.line,
                 column: message.column + blocks[i].position.indent[message.line - 1] - 1

tests/plugin.js

@@ -26,6 +26,7 @@ describe("plugin", function() {
             extensions: ["md", "mkdn", "mdown", "markdown"],
             ignore: false,
             rules: {
+                "eol-last": 2,
                 "no-console": 2
             },
             useEslintrc: false

tests/processor.js

@@ -363,13 +363,13 @@ describe("processor", function() {
         ].join("\n");
         var messages = [
             [
-                { line: 1, column: 1, message: "Use the global form of \"use strict\"." },
-                { line: 3, column: 5, message: "Unexpected console statement." }
+                { line: 1, column: 1, message: "Use the global form of \"use strict\".", ruleId: "strict" },
+                { line: 3, column: 5, message: "Unexpected console statement.", ruleId: "no-console" }
             ], [
-                { line: 3, column: 6, message: "Missing trailing comma." }
+                { line: 3, column: 6, message: "Missing trailing comma.", ruleId: "comma-dangle" }
             ], [
-                { line: 3, column: 2, message: "Unreachable code after return." },
-                { line: 4, column: 2, message: "Unnecessary semicolon." }
+                { line: 3, column: 2, message: "Unreachable code after return.", ruleId: "no-unreachable" },
+                { line: 4, column: 2, message: "Unnecessary semicolon.", ruleId: "no-extra-semi" }
             ]
         ];
 
@@ -418,6 +418,16 @@ describe("processor", function() {
             assert.equal(result[3].column, 2);
             assert.equal(result[4].column, 2);
         });
+
+        it("should exclude eol-last messages", function() {
+            var result = processor.postprocess([
+                [
+                    { line: 4, column: 3, message: "Newline required at end of file but not found.", ruleId: "eol-last" }
+                ]
+            ]);
+
+            assert.equal(result.length, 0);
+        });
     });
 
 });