Implement handleWarnings() method

README.md

@@ -5,13 +5,46 @@ cls-hooked.
 
 ## Main changes in `cls-hooked` branch
 
+The following method (**NOT READY FOR PRODUCTION**) is added: `LoopBackContext.handleWarnings()`.
+
+Example:
+
+```
+// as early as possible in your code:
+var clsHookedInterceptor = require('cls-hooked-interceptor');
+...
+LoopBackContext.handleWarnings(clsHookedInterceptor, callback);
+```
+
+The callback must have the following form:
+
+```
+var callback = function(err) {
+  // do something with err.message, err.code, err.errno
+}
+```
+
+The callback gets called only if and when there is a warning, and only once per warning message.
+
+The possible warning messages and codes are here:
+
+[cls-hooked-interceptor/errors.js](https://github.com/josieusa/cls-hooked-interceptor/blob/09933d4429dd93a1ea095fcadbe978bc2b5519b2/errors.js)
+
+ `LoopBackContext.handleWarnings()` fails if you haven't installed the interceptor module yet (**NOT READY FOR PRODUCTION**) by running something similar to this:
+
+`npm i josieusa/cls-hooked-interceptor`
+
+(For now, `cls-hooked-interceptor` is not published to NPM. Maybe a recent enough version of NPM is required.)
+
+This branch is incompatible with `continuation-local-storage` and silently fails at runtime if that is used somewhere.
+
 The work-in-progress `cls-hooked` branch uses `cls-hooked` NPM package, which in turn uses `async-hook`. The latter requires Node > 4.5 as specified in its own `package.json`. **This change alone doesn't solve, for now, any problem with `loopback-context`, especially issues related to lost context (for example see [loopback #1495](https://github.com/strongloop/loopback/issues/1495)), as far as the writer knows**. But it uses Node `AsyncWrap`, which may have some pros in the long term.
 
 However, as a work-in-progress, this branch also includes the experimental package `cls-hooked-interceptor` (**not ready for production**), which should give useful warnings when there is the risk that the context would get lost at runtime. **Neither this solves any problem with `loopback-context`**. It's just *a work-in-progress that will eventually help with debugging and mantaining apps experiencing such issues, common especially in legacy apps*.
 
 Therefore, **what is the solution to issues with lost context?** For now, you should implement your own solution. For example, the writer uses the `npm shrinkwrap` solution mentioned in [loopback #1495](https://github.com/strongloop/loopback/issues/1495), but even this could be useless for you, in case you get a broken install (this is unpredictable and hard to notice, and this package wants to change that).
 
-To test this branch, just run the tests with `npm test`. (You will also see a warning from `cls-hooked-interceptor`, in addition to the test output; this is the desired behavior).
+To test this branch, just run the tests with `npm test`. (You will also see a warning from `cls-hooked-interceptor`, in addition to the `cls-hooked-interceptor` suite output - and only that suite; this is the desired behavior).
 
 If you want to see all the infos and warnings that `cls-hooked-interceptor` sends to the `debug` package, declare the environment variable `DEBUG=cls-hooked-interceptor` when running the tests.
 
@@ -19,7 +52,7 @@ OS X example:
 
 `DEBUG=cls-hooked-interceptor npm test`
 
-By default, the test makes the context get lost. If you want to test the opposite case when the package does *not* warn, because the context is *not* lost, just declare the environment variable `KEEP_CONTEXT=true` when running the tests (*this variable has no effect outside of tests!*).
+By default, the test makes the context get lost. If you want to test the opposite case when the package does *not* warn, because the context is *not* lost, just declare the environment variable `KEEP_CONTEXT=true` when running the tests (*this variable has no effect outside of tests!*). Of course, no warning will be logged to the console!
 
 OS X example:
 

package.json

@@ -28,6 +28,7 @@
   "devDependencies": {
     "async": "1.5.2",
     "chai": "^3.5.0",
+    "chai-spies": "0.7.1",
     "dirty-chai": "^1.2.2",
     "eslint": "^2.13.1",
     "eslint-config-loopback": "^4.0.0",

server/current-context.js

@@ -116,3 +116,7 @@ LoopBackContext.createContext = function(scopeName) {
   }
   return ns;
 };
+
+LoopBackContext.handleWarnings = function(clsHookedInterceptorInstance, cb) {
+  clsHookedInterceptorInstance(cb);
+};

test/main.test.js

@@ -18,6 +18,11 @@ var Domain = require('domain');
 var EventEmitter = require('events').EventEmitter;
 var expect = require('./helpers/expect');
 var request = require('supertest');
+var spies = require('chai-spies');
+var chai = require('chai');
+var clsHookedInterceptor;
+
+chai.use(spies);
 
 describe('LoopBack Context', function() {
   var runInOtherDomain, runnerInterval;
@@ -174,3 +179,14 @@ describe('cls-hooked-interceptor', function() {
     });
   });
 });
+
+describe('LoopBack Context', function() {
+  it('replaces cls-hooked-interceptor callback', function() {
+    var cb = function() {};
+    var spy = chai.spy(cb);
+    ClsContext.handleWarnings(require('cls-hooked-interceptor'), spy);
+    // trick cls-hooked-interceptor
+    require('async');
+    expect(spy).to.have.been.called();
+  });
+});