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raineorshine/assert-throw.js

Last active March 16, 2019 18:37
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Asserting solidity throws in truffle tests.
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assert-throw.js
it('should throw an error', cb => {
const result = aMethodThatRejects()
result.then(x => { cb('Expected error. Instead got ' + x) }))
result.catch(() => cb())
})
@raineorshine
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In newer versions of node, the originally suggested approach will result in unhandled rejections. They can be suppressed, but a cleaner approach is one of the following:

Promise:

return aMethodThatRejects().then(
  () => Promise.reject(new Error('Expected method to reject.')),
  err => assert.instanceOf(err, Error)
)

With Chai:

aMethodThatRejects().should.eventually.be.rejectedWith('ERROR');

Reference: https://gist.github.com/haroldtreen/5f1055eee5fcf01da3e0e15b8ec86bf6

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