"uncovered code" warning from flow

[nitingupta910]

Although I'm not getting any error when using idx, I'm getting "uncovered code" wherever idx is used. Using flow 0.61.0, idx 2.2.0, babel-plugin-idx: 2.2.0.

Example:

index.js

// @flow
import idx from 'idx';

type User = {
    user: ?{
        name: string,
        friends: ?Array<User>,
    }
};

const props: User = { user: null };

// Uncovered code warning from flow for arrow function below
idx(props, _ => _.user.friends[0].user.friends)

flow coverage index.js 
Covered: 56.25% (9 of 16 expressions)

flow coverage index.js --pretty
{
  "expressions":{
    "covered_count":9,
    "uncovered_count":7,
    "uncovered_locs":[
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":12,"offset":232},
        "end":{"line":14,"column":12,"offset":233}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":17,"offset":238}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":22,"offset":243}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":30,"offset":251}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":33,"offset":254}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":38,"offset":259}
      },
      {
        "source":"/Users/ngupta/progjs/idx_sample/index.js",
        "type":"SourceFile",
        "start":{"line":14,"column":17,"offset":237},
        "end":{"line":14,"column":46,"offset":267}
      }
    ]
  }
}

[panagosg7]

Hi @nitingupta910!

This has probably been addressed in more recent versions of Flow, since I cannot reproduce your case. I'm using Flow version v0.71.0 and idx@2.3.0 which I installed through yarn. Then I did:

$ flow coverage index.js
Covered: 100.00% (16 of 16 expressions)

Note that:

$ flow type-at-pos index.js 2 9
$Facebookism$Idx
index.js:2:8,2:10

and

flow type-at-pos index.js 14 42
?Array<User>
index.js:14:40,14:46

[nitingupta910]

@panagosg7 I just moved my codebase to typescript so can't verify this, anyways thanks for looking into it.