istanbul.json

{
  "/main.js": {
    "path": "/main.js",
    "statementMap": {
      "s0": {
        "start": {
          "line": 1,
          "column": 0
        },
        "end": {
          "line": 10,
          "column": 3
        }
      },
      "s1": {
        "start": {
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          "column": 0
        },
        "end": {
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          "column": 3
        }
      },
      "s2": {
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        },
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        }
      },
      "s3": {
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        },
        "end": {
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        }
      }
    },
    "s": {
      "s0": 1,
      "s1": 1,
      "s2": 1,
      "s3": 1
    },
    "fnMap": {
      "f0": {
        "start": {
          "line": 1,
          "column": 1
        },
        "end": {
          "line": 10,
          "column": 1
        }
      },
      "f1": {
        "start": {
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          "column": 39
        },
        "end": {
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      }
    },
    "f": {
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    },
    "branchMap": {},
    "b": {}
  }
}

main.js

const Bluebird = require("bluebird");
const fs = require("fs");

readTextFileAsync = Bluebird.promisify(function (params, cb) {
  fs.readFile(params, "UTF-8", cb);
});

readTextFileAsync("./main.js")