Invalid value error thrown on intersection value within struct

[chrisui]

Version

3.2.3

Expected behaviour

Should not error on intersection type as property of struct.

Actual behaviour

Invalid value error.

/Users/chris/Projects/testtest/node_modules/tcomb/lib/fail.js:2
  throw new TypeError('[tcomb] ' + message);
  ^

TypeError: [tcomb] Invalid value {
  "string": "Test"
} supplied to Struct{a: Struct{string: {String | <function1>}} & Struct{string: {String | <function1>}}}/a: Struct{string: {String | <function1>}} & Struct{string: {String | <function1>}}
    at Function.fail (/Users/chris/Projects/testtest/node_modules/tcomb/lib/fail.js:2:9)
    at assert (/Users/chris/Projects/testtest/node_modules/tcomb/lib/assert.js:14:12)
    at Intersection (/Users/chris/Projects/testtest/node_modules/tcomb/lib/intersection.js:27:7)
    at create (/Users/chris/Projects/testtest/node_modules/tcomb/lib/create.js:10:66)
    at new Struct (/Users/chris/Projects/testtest/node_modules/tcomb/lib/struct.js:82:19)
    at Object.validateStruct [as struct] (/Users/chris/Projects/testtest/node_modules/tcomb-validation/index.js:173:17)
    at recurse (/Users/chris/Projects/testtest/node_modules/tcomb-validation/index.js:71:38)
    at Function.validate (/Users/chris/Projects/testtest/node_modules/tcomb-validation/index.js:66:31)
    at Object.<anonymous> (/Users/chris/Projects/testtest/run.js:28:18)
    at Module._compile (module.js:413:34)

Steps to reproduce

Run the following code (note how the alternative commented lines work fine):

const t = require('tcomb-validation');

const Min = t.refinement(t.String, (s) => s.length > 2);
const Max = t.refinement(t.String, (s) => s.length < 5);

const TypeA = t.struct({string: Min});
const TypeB = t.struct({string: Max});

const Type = t.struct({
  test: t.intersection([TypeA, TypeB])
});

const val = {
  test: {
    string: 'Test'
  }
};

//const Type = t.intersection([TypeA, TypeB]);
//const val = {string: 'Test'};

const result = t.validate(val, Type);
console.log(result);

Stack trace and console log

Will follow up with this if required!

Thanks in advance! :)

Ps. Sorry if this is wrong repo, my guess was this is more core tcomb rather than actually validation related

[gcanti]

Hi @chrisui,

thanks for the detailed report. This is an edge case: please note how, since structs are nominal (i.e. their is functions are implemented with instanceof) this set is empty:

t.intersection([TypeA, TypeB])

so, from a theoretical point of view, the current behavior is correct.

I suggest to use interface instead of struct:

const Min = t.refinement(t.String, (s) => s.length > 2);
const Max = t.refinement(t.String, (s) => s.length < 5);

const TypeA = t.interface({string: Min}); // <= interface
const TypeB = t.interface({string: Max}); // <= interface

const Type = t.struct({
  test: t.intersection([TypeA, TypeB])
});

const val = {
  test: {
    string: 'Test'
  }
};

const result = t.validate(val, Type);
console.log(result);

The alternative commented lines work fine because... you have actually found a bug in tcomb-validation so this issue is in the right wrong place :)

[chrisui]

Gotcha! Thanks for the aid and glad to be of some help. ;)

[gcanti]

Closing in favour of gcanti/tcomb-validation#42