fix(eslint-plugin): [no-unnecessary-condition] improve optional chain handling 2 - electric boogaloo #2138
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Codecov Report
@@ Coverage Diff @@
## master #2138 +/- ##
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+ Coverage 93.54% 93.56% +0.01%
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Files 171 171
Lines 7798 7811 +13
Branches 2225 2229 +4
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+ Hits 7295 7308 +13
Misses 244 244
Partials 259 259
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| const ownPropertyType = prevType.types | ||
| .map(type => checker.getTypeOfPropertyOfType(type, property.name)) | ||
| .find(t => t); |
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Mapping over the types in the union isn't quite right, and will cause issues in the following case. The checker API is smart enough to analyse unions to get the type of a property on that union.
interface Foo {
a: number;
}
interface Bar {
a: string | null;
}
declare const x: Foo | Bar;# type = type of x;
$ type.types.map(t => checker.typeToString(checker.getTypeOfPropertyOfType(t, 'a')))
> ["number", "string | null"]Eg with your current logic, this case will just check the number case, and will thus false-positive on the property.
If you instead just ask for the property on the union type itself:
# type = type of x;
$ checker.typeToString(checker.getTypeOfPropertyOfType(type, 'a'))
> "string | number | null"It will work as expected. However if for some reason the base type is nullish, you need to also scrub the null from the union first:
interface Foo {
a: number;
}
interface Bar {
a: string | null;
}
declare const x: {t: Foo | Bar} | null;
x?.t.a;# type = type of x?.t;
$ nonNullType = checker.getNonNullableType(type)
$ checker.typeToString(checker.getTypeOfPropertyOfType(nonNullType, 'a'))
> "string | number | null"There was a problem hiding this comment.
@bradzacher
Thanks for the review. I'll change it soon :)
Fixes #1977
#1977 occurs when member expression's nullable type is originated from the previous node.
So, I changed it to check whether a member expression's nullable type is origin from its previous.