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Add a warning for undefined properties passed to combineReducers #1789

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Merged
timdorr merged 4 commits into from
Jul 19, 2016
Merged

Add a warning for undefined properties passed to combineReducers #1789

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88b0591
Add warning to combineReducers for undefined properties
borkxs Jun 3, 2016
4ca4595
Test that it warns for undefined reducer props
borkxs Jun 8, 2016
ec3752b
Duh remove only
borkxs Jun 8, 2016
f9bcf20
add some newlines
borkxs Jul 19, 2016
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5 changes: 5 additions & 0 deletions src/combineReducers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,11 @@ export default function combineReducers(reducers) {
var finalReducers = {}
for (var i = 0; i < reducerKeys.length; i++) {
var key = reducerKeys[i]
if (process.env.NODE_ENV !== 'production') {
if (typeof reducers[key] === 'undefined') {
warning(`No reducer provided for key "${key}"`)
}
}
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@timdorr timdorr Jul 19, 2016

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Nit: Do you mind adding newlines before and after this new block? It makes it easier to spot the dev-only code.

if (typeof reducers[key] === 'function') {
finalReducers[key] = reducers[key]
}
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18 changes: 18 additions & 0 deletions test/combineReducers.spec.js
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Expand Up @@ -31,6 +31,24 @@ describe('Utils', () => {
).toEqual([ 'stack' ])
})

it('warns if a reducer prop is undefined', () => {
const spy = expect.spyOn(console, 'error')

let isNotDefined
combineReducers({ isNotDefined })
expect(spy.calls[0].arguments[0]).toMatch(
/No reducer provided for key "isNotDefined"/
)

spy.reset()
combineReducers({ thing: undefined })
expect(spy.calls[0].arguments[0]).toMatch(
/No reducer provided for key "thing"/
)

spy.restore()
})

it('throws an error if a reducer returns undefined handling an action', () => {
const reducer = combineReducers({
counter(state = 0, action) {
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