[[FIX]] Correct CLI's indentation offset logic

Don't attempt to indent errors using data from other files, during
extract with multiple files

This change will fix the report of `col NaN` and the problem of `NaN` in
`error.character` while checking JS code extracted from non-JS files,
when more than one file has been passed in and their lengths don't
match.

The function `extractOffsets` finds the number of characters a JS block
must be shifted to show the correct character column for an error. The
result is an array consisting of numbers, for the block it checked and,
`undefined` for the lines it didn't have to look at.  `cli.run` executes
`extractOffsets` on each input file but wrongly tries to indent all the
errors found so far, across files, using the current file's offsets.
This commit makes sure `cli.run` only indents errors of a file against
the offsets fetched for the same file.

This commit also makes sure that we don't change or ruin the value of
`error.character` unnecessarily.

I have chosen to trust that `extractOffsets` will return an array with
only numbers (as a result of Array.length) and falsy values, to avoid
the unnecessary type conversion.

A test named `usingMultipleFiles` has been introduced to cli.

Fixes #2778

src/cli.js

@@ -642,6 +642,7 @@ var exports = {
     files.forEach(function(file) {
       var config = opts.config || exports.getConfig(file);
       var code;
+      var errors = [];
 
       try {
         code = shjs.cat(file);
@@ -652,19 +653,20 @@ var exports = {
 
       mergeCLIPrereq(config);
 
-      lint(extract(code, opts.extract), results, config, data, file);
+      lint(extract(code, opts.extract), errors, config, data, file);
 
-      if (results.length) {
+      if (errors.length) {
         var offsets = extractOffsets(code, opts.extract);
         if (offsets && offsets.length) {
-          results.forEach(function(errorInfo) {
+          errors.forEach(function(errorInfo) {
             var line = errorInfo.error.line;
-            if (line >= 0 && line < offsets.length) {
-              var offset = +offsets[line];
-              errorInfo.error.character += offset;
+            if (line >= 0 && line < offsets.length && offsets[line]) {
+              errorInfo.error.character += offsets[line];
             }
           });
         }
+
+        results = results.concat(errors);
       }
     });
 

tests/cli.js

@@ -633,7 +633,7 @@ exports.group = {
 
     test.done();
   },
-  
+
   testMultipleIgnores: function (test) {
     var run = this.sinon.stub(cli, "run");
     var dir = __dirname + "/../examples/";
@@ -642,10 +642,10 @@ exports.group = {
     cli.interpret([
       "node", "jshint", "file.js", "--exclude=foo.js,bar.js"
     ]);
-    
+
     test.equal(run.args[0][0].ignores[0], path.resolve(dir, "foo.js"));
     test.equal(run.args[0][0].ignores[1], path.resolve(dir, "bar.js"));
-    
+
     test.done();
   },
 
@@ -1152,6 +1152,51 @@ exports.extract = {
     test.done();
   },
 
+  usingMultipleFiles: function (test) {
+    var rep = require("../examples/reporter.js");
+    var errors = [];
+    this.sinon.stub(rep, "reporter", function (res) {
+      errors = errors.concat(res);
+    });
+
+    var dir = __dirname + "/../examples/";
+    this.sinon.stub(process, "cwd").returns(dir);
+
+    var html = [
+      "<script type='text/javascript'>",
+      "  a()",
+      "</script>",
+    ].join("\n");
+
+    this.sinon.stub(shjs, "cat")
+      .withArgs(sinon.match(/indent\.html$/)).returns(html)
+      .withArgs(sinon.match(/another\.html$/)).returns("\n\n<script>a && a();</script>");
+
+    this.sinon.stub(shjs, "test")
+      .withArgs("-e", sinon.match(/indent\.html$/)).returns(true)
+      .withArgs("-e", sinon.match(/another\.html$/)).returns(true);
+
+    cli.interpret([
+      "node", "jshint", "indent.html", "another.html", "--extract", "auto", "--reporter=reporter.js"
+    ]);
+    test.equal(cli.exit.args[0][0], 2);
+
+    test.equal(errors.length, 2, "found two errors");
+    var lintError = errors[0].error;
+    test.ok(lintError, "have error object");
+    test.equal(lintError.code, "W033", "found missing semicolon warning");
+    test.equal(lintError.line, 2, "misaligned line");
+    test.equal(lintError.character, 6, "first misaligned character at column 2");
+
+    lintError = errors[1].error;
+    test.ok(lintError, "have error object");
+    test.equal(lintError.code, "W030", "found an expression warning");
+    test.equal(lintError.line, 3, "misaligned line");
+    test.equal(lintError.character, 8, "first misaligned character at column 8");
+
+    test.done();
+  },
+
   "\\r\\n as line terminator (gh-2825)": function (test) {
     var html = [
       "<script>",