AssertionError [ERR_ASSERTION]: 'newBasePath' should be an absolute path

Windows Node v12.13.0 npm v6.13.6 eslint 6.8.0 Parser: @typescript-eslint/parser Bash terminal

eslint config:

"use strict";
const allExtensions = [".ts", ".tsx", ".d.ts", ".js", ".jsx"];
module.exports = {
    env: {
        "browser": true,
        "es6": true,
    },
    parser: "@typescript-eslint/parser",
    parserOptions: {
        project: "./tsconfig.json",
        sourceType: "module",
    },
    plugins: [
        "import",
        "@typescript-eslint",
        "@typescript-eslint/tslint",
    ],
    settings: {
        "import/extensions": allExtensions,
        "import/parsers": {
            "@typescript-eslint/parser": [".ts", ".tsx", ".d.ts"],
        },
        "import/resolver": {
            "node": {
                "extensions": allExtensions,
            },
        },
    },
    rules: {
     
        "import/no-deprecated": "warn",
        "@typescript-eslint/no-unused-vars": "error",
        "@typescript-eslint/tslint/config": [
            "warn",
            {
                "rules": {
                    "deprecation": true,
                },
            },
        ],
    },
};

I’m currently using a globally installed npm package (call it foo cli) that wraps eslint. I have a workspace in c:\src\myproject. foo cli has an internal reference to eslint 6.8.0. When I run ap lint from c:\src\myproject, foo cli invokes eslint with some default parameters, and I get the error from the bug title. Here’s the raw output:

/c/myproject (master)
$ ap lint
Running C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\.bin\eslint.cmd **/*.ts --ignore-path C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintignore -c C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintrc.json --resolve-plugins-relative-to C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint
AssertionError [ERR_ASSERTION]: 'newBasePath' should be an absolute path.
    at IgnorePattern.getPatternsRelativeTo (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:210:9)
    at C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:150:42
    at Array.map (<anonymous>)
    at Function.createIgnore (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:150:31)
    at createConfig (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\config-array.js:282:40)
    at ConfigArray.extractConfig (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\config-array.js:452:33)
    at FileEnumerator._isIgnoredFile (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:479:24)
    at FileEnumerator._iterateFilesRecursive (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:407:38)
    at _iterateFilesRecursive.next (<anonymous>)
    at FileEnumerator.iterateFiles (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:251:49)

I believe the problem exists in ignore-pattern.js and was introduced in this pull request: https://github.com/eslint/eslint/pull/12274/files

If I add some debug logging to IgnorePattern.getCommonAncestorPath:

function getCommonAncestorPath(sourcePaths) {
    let result = sourcePaths[0];

    for (let i = 1; i < sourcePaths.length; ++i) {
        const a = result;
        const b = sourcePaths[i];

        // Set the shorter one (it's the common ancestor if one includes the other).
        result = a.length < b.length ? a : b;

        // Set the common ancestor.
        for (let j = 0, lastSepPos = 0; j < a.length && j < b.length; ++j) {
            if (a[j] !== b[j]) {
                result = a.slice(0, lastSepPos);
                break;
            }
            if (a[j] === path.sep) {
                lastSepPos = j;
            }
        }
    }
    console.log("**: ", { result: result, sep: path.sep, sourcePaths: sourcePaths }); // new line here
    return result || path.sep;
}

I see the following output:

/c/myproject (master)
$ ap lint
Running C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\.bin\eslint.cmd **/*.ts --ignore-path C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintignore -c C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintrc.json --resolve-plugins-relative-to C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint
**:  {
  result: 'C:\\src\\myproject',
  sep: '\\',
  sourcePaths: [ 'C:\\src\\myproject' ]
}
**:  {
  result: 'C:\\src\\myproject',
  sep: '\\',
  sourcePaths: [ 'C:\\src\\myproject' ]
}
**:  {
  result: 'C:',
  sep: '\\',
  sourcePaths: [
    'C:\\src\\myproject',
    'C:\\Users\\drkestel\\AppData\\Roaming\\npm\\node_modules\\@foocli\\lint'
  ]
}
AssertionError [ERR_ASSERTION]: 'newBasePath' should be an absolute path.
    at IgnorePattern.getPatternsRelativeTo (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:210:9)
    at C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:150:42
    at Array.map (<anonymous>)
    at Function.createIgnore (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\ignore-pattern.js:150:31)
    at createConfig (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\config-array.js:282:40)
    at ConfigArray.extractConfig (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\config-array\config-array.js:452:33)
    at FileEnumerator._isIgnoredFile (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:479:24)
    at FileEnumerator._iterateFilesRecursive (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:407:38)
    at _iterateFilesRecursive.next (<anonymous>)
    at FileEnumerator.iterateFiles (C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\eslint\lib\cli-engine\file-enumerator.js:251:49)

/c/myproject (master)
$

Notice the result: 'C:', - that is not considered a valid absolute path.

Interestingly enough, I can mitigate the problem by using windows cmd.exe and setting my current prompt to c:\ (lowercase, as opposed to C:\). Because c:\ != C:\, it works. See the output:

c:\src\myproject>ap lint
Running C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\node_modules\.bin\eslint.cmd **/*.ts --ignore-path C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintignore -c C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint\.eslintrc.json --resolve-plugins-relative-to C:\Users\drkestel\AppData\Roaming\npm\node_modules\@foocli\lint
**:  {
  result: 'c:\\src\\myproject',
  sep: '\\',
  sourcePaths: [ 'c:\\src\\myproject' ]
}
**:  {
  result: 'c:\\src\\myproject',
  sep: '\\',
  sourcePaths: [ 'c:\\src\\myproject' ]
}
**:  {
  result: '',
  sep: '\\',
  sourcePaths: [
    'c:\\src\\myproject',
    'C:\\Users\\drkestel\\AppData\\Roaming\\npm\\node_modules\\@foocli\\lint'
  ]
}
**:  {
  result: '',
  sep: '\\',
  sourcePaths: [
    'c:\\src\\myproject',
    'C:\\Users\\drkestel\\AppData\\Roaming\\npm\\node_modules\\@foocli\\lint'
  ]
}

c:\src\myproject\Client\Index.ts
  66:5   warning  Missing return type on function                 @typescript-eslint/explicit-function-return-type
  67:17  error    'container' is assigned a value but never used  @typescript-eslint/no-unused-vars
  68:15  error    'id' is assigned a value but never used         @typescript-eslint/no-unused-vars

... more valid linting

I can also mitigate the problem by making the following code change to ignore-pattern.js:

function getCommonAncestorPath(sourcePaths) {
    let result = sourcePaths[0];

    for (let i = 1; i < sourcePaths.length; ++i) {
        const a = result;
        const b = sourcePaths[i];

        // Set the shorter one (it's the common ancestor if one includes the other).
        result = a.length < b.length ? a : b;

        // Set the common ancestor.
        for (let j = 0, lastSepPos = 0; j < a.length && j < b.length; ++j) {
            if (a[j] !== b[j]) {
                result = a.slice(0, lastSepPos);
                break;
            }
            if (a[j] === path.sep) {
                lastSepPos = j;
            }
        }
    }
    // this was the previous return statement
    // return result || path.sep;

    // new return statement
    let resolvedResult = result || path.sep;
    if (resolvedResult && resolvedResult.endsWith(":")) {
        resolvedResult = resolvedResult + path.sep;
    }
    return resolvedResult;
}

[kaicataldo]

Thanks for the detailed bug report. This does seem like a bug to me. Looking at how paths work in WIndows in Microsoft’s documentation, it does look like we need to fix this algorithm to not remove the separator from C:, since "C:" is considered relative while "C:\\" is considered absolute.

[nickharris]

yup already using it 😃 thank you!