Fix instrumentation in shallow rendering

[sophiebits]

Previously, this threw:

 FAIL  src/test/__tests__/ReactTestUtils-test.js (7.291s)
● ReactTestUtils › it can fail context when shallowly rendering
  - TypeError: Cannot read property '_source' of null
        at describeID (src/renderers/shared/devtools/ReactComponentTreeDevtool.js:70:46)
        at Object.ReactComponentTreeDevtool.getStackAddendumByID (src/renderers/shared/devtools/ReactComponentTreeDevtool.js:203:15)
        at checkReactTypeSpec (src/isomorphic/classic/types/checkReactTypeSpec.js:76:58)
        at ReactCompositeComponentMixin._checkContextTypes (src/renderers/shared/stack/reconciler/ReactCompositeComponent.js:668:5)
        at ReactCompositeComponentMixin._processContext (src/renderers/shared/stack/reconciler/ReactCompositeComponent.js:607:14)
        at ReactCompositeComponentMixin.mountComponent (src/renderers/shared/stack/reconciler/ReactCompositeComponent.js:191:30)
        at ReactShallowRenderer._render (src/test/ReactTestUtils.js:483:14)
        at _batchedRender (src/test/ReactTestUtils.js:460:12)
        at ReactDefaultBatchingStrategyTransaction.Mixin.perform (src/shared/utils/Transaction.js:140:20)
        at Object.ReactDefaultBatchingStrategy.batchedUpdates (src/renderers/shared/stack/reconciler/ReactDefaultBatchingStrategy.js:65:19)
        at Object.batchedUpdates (src/renderers/shared/stack/reconciler/ReactUpdates.js:112:20)
        at ReactShallowRenderer.render (src/test/ReactTestUtils.js:453:16)
        at Spec.eval (src/test/__tests__/ReactTestUtils-test.js:289:34)
        at jasmine.Block.execute (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:1067:17)
        at jasmine.Queue.next_ (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2100:31)
        at jasmine.Queue.start (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2053:8)
        at Spec.jasmine.Spec.execute (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2380:14)
        at jasmine.Queue.next_ (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2100:31)
        at onComplete (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2096:18)
        at Spec.jasmine.Spec.finish (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2354:5)
        at eval [as onComplete] (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2381:10)
        at jasmine.Queue.next_ (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2110:14)
        at eval (node_modules/jest-jasmine1/vendor/jasmine-1.3.0.js:2090:18)
        at Timeout.e [as _onTimeout] (node_modules/jsdom/lib/jsdom/browser/Window.js:440:19)
        at tryOnTimeout (timers.js:224:11)
        at Timer.listOnTimeout (timers.js:198:5)

@gaearon

[sophiebits]

As a follow-up, I'll look at making this not throw when element is missing.

[gaearon]

As a follow-up, I'll look at making this not throw when element is missing.

👍

This would be consistent with the “sane defaults” we have for other tree devtool getters.

[sophiebits]

Well I was going to make it warn. :) Because I think it should probably never be missing when we want to use it.

[gaearon]

I wonder if we should warn consistently for other getters too? Ideally nobody should be asking about things that don’t exist.

[sophiebits]

That sounds pretty reasonable.