I see the same issue.

$ ng lint
/Users/john/_play/angular-hello/src/app/app.component.ts[13, 5]: Identifier 'f' is never reassigned; use 'const' instead of 'let'.
/Users/john/_play/angular-hello/src/app/app.component.ts[13, 5]: Identifier 'f' is never reassigned; use 'const' instead of 'let'.
Lint errors found in the listed files.

$ ng -v --verbose
    _                      _                 ____ _     ___
   / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
  / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
 / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
/_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
               |___/
@angular/cli: 1.0.0-rc.1
http_parser: 2.7.0
node: 6.9.1
v8: 5.1.281.84
uv: 1.9.1
zlib: 1.2.8
ares: 1.10.1-DEV
icu: 57.1
modules: 48
openssl: 1.0.2j
os: darwin x64
@angular/common: 4.0.0-rc.2
@angular/compiler: 4.0.0-rc.2
@angular/core: 4.0.0-rc.2
@angular/flex-layout: 2.0.0-rc.1
@angular/forms: 4.0.0-rc.2
@angular/http: 4.0.0-rc.2
@angular/material: 2.0.0-beta.2
@angular/platform-browser: 4.0.0-rc.2
@angular/platform-browser-dynamic: 4.0.0-rc.2
@angular/router: 4.0.0-rc.2
@angular/cli: 1.0.0-rc.1
@angular/compiler-cli: 4.0.0-rc.2

as per chat with @filipesilva , this may be due to the multiple TS projects now included in the CLI.

It seems like the linter runs once for each project? and since the tests should include the same components it is hitting the same code twice

It seems that there's again a similar issue with @angular/cli@6.0.3 now, can someone confirm?

After some tests, I found that commenting one of the two tsConfig entry in angular.json result to output the error one time. Maybe the linter run twice on files included in spec AND in app config ?

Same problem for me. Included two tsConfigs in angular.json:

        "lint": {
          "builder": "@angular-devkit/build-angular:tslint",
          "options": {
            "tsConfig": [
              "src/tsconfig.app.json",
              "src/tsconfig.spec.json"
            ],
            "exclude": [
              "**/node_modules/**"
            ]
          }
        }

If tsconfig.spec.json includes all the files that tsconfic.app.json does, then specifying only tsconfig.spec.json in the linting config in angular.json is enough to lint everything perfectly:

"lint": {
 "builder": "@angular-devkit/build-angular:tslint",
  "options": {
    "tsConfig": "src/tsconfig.spec.json",
    "typeCheck": true,
    "format": "stylish"
  }
}

I'd love to have a chance to include both spec and app tsconfigs of my project inside of angular.json/lint options, without caring about their content. Solution above is more like a temporary workaround (I have to admit it works fine), not a state we'd like to see here for ever IMO.

(I see that PR is still closed - is anyone aware of this issue?)

CC: @filipesilva

I'm also having duplicated error messages when running this:

ng lint --format=stylish --force my-app my-app-e2e

Any solution or workaround available?

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