Loading Files Dynamically and --hook-run-in-context documentation?

[jtibble]

I'm loading JS in my Mocha test at runtime using fs and vm.runInThisContext:

fs.readFile(path, {encoding: 'utf8'}, function(error, data){})
....
vm.runInThisContext( code );

but when I run istanbul like so

$ istanbul cover --hook-run-in-context node_modules/mocha/bin/_mocha -- --recursive -R spec
...
  fake test
    √ should pass

  3 passing (28ms)

No coverage information was collected, exit without writing coverage information

Is there any documentation for how to use the --hook-run-in-context command to get code-coverage for these files?

(Windows 7 with Git Bash)

$ node -v && npm -v
v0.12.2
2.7.4
$ npm list -g mocha
C:\Users\212309975\AppData\Roaming\npm
└── mocha@2.2.4

[davglass]

This should cover the code that is passed into the runInThisContext method. Do you have a repro case that I can look at?

[tswaters]

I just encountered this issue

Based on the node api docs, I was trying the following.... While it worked when running the tests, istanbul was not picking it up.

var fileName = './path/to/file.js';
vm.runInThisContext(fs.readFileSync(fileName), {filename: path.resolve(fileName)});

So I dug into the istanbul code a bit -- hookRunInThisContext leaves a few things to be desired :

• the first parameter must be a string. buffers will not be accepted -- ("[Error: Code must be string]") -- if you call toString on the buffer, this seems to work fine
• filename must be provided as the second parameter to vm.runInThisContext -- without it, the code will not be transformed.

The second bullet is concerning because no where in the node docs does it say to pass a string as the second parameter to runInThisContext - it doesn't die when you do which is I suppose a silver lining... it should accept an object hash of which filename can be included.

I had to rework the above example to the following to get istanbul to recognize it:

var fileName = './path/to/file.js';
vm.runInThisContext(fs.readFileSycn(fileName).toString(), path.resolve(fileName))

I would think within the hook itself, two changes are required:

• it should call toString on code
• it should read filename from the second parameter. It seems to me istanbul would require the filename to be present and should throw a warning or some such if the options object was not provided or does not include a filename.

[tswaters]

Here we go --

diff --git a/lib/hook.js b/lib/hook.js
index 4ec9dc5..44ecf18 100644
--- a/lib/hook.js
+++ b/lib/hook.js
@@ -169,9 +169,12 @@ function unhookCreateScript() {
 function hookRunInThisContext(matcher, transformer, opts) {
     opts = opts || {};
     var fn = transformFn(matcher, transformer, opts.verbose);
-    vm.runInThisContext = function (code, file) {
-        var ret = fn(code, file);
-        return originalRunInThisContext(ret.code, file);
+    vm.runInThisContext = function (code, opts) {
+        if (!opts || !opts.filename) {
+          console.error('vm.runInThisContext called without opts.filename')
+        }
+        var ret = fn(code.toString(), (opts || {}).filename);
+        return originalRunInThisContext(ret.code, opts);
     };
 }

I was going to send a PR, but it seems many of the tests after checking out master are failing on Windows -- I'm unsure as to what unrelated things might fail as part of this.

[jtibble]

Great work, @tswaters! Since creating this issue I've changed jobs and now rarely work with NodeJS, but when I get back into it I'll see if I can get this working again with your diff.

Cheers, John