console.log(require.cache) fails when koa is present

[paulpflug]

koa = require('koa')
console.log(require.cache)

will fail because of the custom inspect implementation in context.js, which uses the custom toJSON, which relies on a properly set this, which is not the case.

not very important. But noteworthy - I guess
At least is costed me some time to figure it out.

[skbolton]

I've been chasing down multiple angles at this and I can't seem to get my finger on whats going on.
console.dir(require.cache) works fine.require.cache even works fine as a variable for whatever reason console.log clashes with inspect() inside of context.js.

[skbolton]

Found the culprit
In nodes documentation of util.js package starting at line 342

// Provide a hook for user-specified inspect functions.
  // Check that value is an object with an inspect function on it
  if (ctx.customInspect && value) {
    const maybeCustomInspect = value[customInspectSymbol] || value.inspect;

    if (typeof maybeCustomInspect === 'function' &&
        // Filter out the util module, its inspect function is special
        maybeCustomInspect !== exports.inspect &&
        // Also filter out any prototype objects using the circular check.
        !(value.constructor && value.constructor.prototype === value)) {
      let ret = maybeCustomInspect.call(value, recurseTimes, ctx);

      // If the custom inspection method returned `this`, don't go into
      // infinite recursion.
      if (ret !== value) {
        if (typeof ret !== 'string') {
          ret = formatValue(ctx, ret, recurseTimes);
        }
        return ret;
      }
    }
  }

When require.cache is called with console.log there is a lot of formatting that is done and apparently if a module exports an inspect property they will use that for the formatting. So if this corner case is important than the exported value shoule either not be an object (which is why changing it to a class worked), or change the name of inspect to something different.

[juliangruber]

this was discussed before, and while I can't remember the exact issue we decided this is a node problem and we want to keep our inspect property

[PlasmaPower]

I don't think we discussed this exact question before, but we probably did discuss this being undefined with another function. https://github.com/koajs/koa/issues?utf8=%E2%9C%93&q=is%3Aissue%20inspect%20OR%20toJSON%20

Since this is more builtin to Node and doesn't involve rebinding functions manually I'm more inclined to support it.

[skbolton]

Well if #605 happens (changing from a shared object to a class) then this error will be gone as well.

[PlasmaPower]

@skbolton you can use the #605 which automatically links the issue or pull request: #605 (also your link doesn't work)

[skbolton]

Learn something everyday, fixed.