0% coverage for files only containing TypeScript interfaces #494

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1. bcoe

   added

   bug

   needs more info

   on Oct 25, 2023
2. bcoe commented on Oct 25, 2023

   

   bcoe

   on Oct 25, 2023

   Owner

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   @Xerillio could you please provide a reproduction for this issue.
3. Xerillio commented on Oct 25, 2023

   

   Xerillio

   on Oct 25, 2023

   Last edited by Xerillio

   Author

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   @bcoe You got it 😉

   /package.json:

   {
     "scripts": {
       "test": "mocha -r ts-node/register './tests/**/*.test.ts'",
       "coverage": "c8 npm test"
     },
     "devDependencies": {
       "@types/chai": "^4.3.9",
       "@types/mocha": "^10.0.3",
       "c8": "^8.0.1",
       "chai": "^4.3.10",
       "mocha": "^10.2.0",
       "ts-node": "^10.9.1",
       "typescript": "^5.2.2"
     }
   }

   /tsconfig.json:

   {
     "compilerOptions": {
       "target": "es6",
       "module": "commonjs",
       "esModuleInterop": true,
       "strict": true
     }
   }

   /.c8rc.json:

   {
       "all": true,
       "src": ["./src"],
       "extension": [".ts"],
       "report-dir": "./coverage"
   }

   /src/power.ts:

   import type { IPower } from "./ipower";
   
   export class Power implements IPower {
     calculate(base: number, exponent: number): number {
       if (!Number.isInteger(exponent)) throw new Error("The exponent must be an integer");
   
       let result = 1;
       for (let i = 0; i < exponent; i++) {
         result *= base;
       }
   
       return result;
     }
   }

   /src/ipower.ts:

   export interface IPower {
     calculate(base: number, exponent: number): number
   }

   /tests/power.test.ts:

   import { Power } from "../src/power";
   import { expect } from "chai";
   
   describe("Power", () => {
     describe("#calculate", () => {
         it("should return 1 when the exponent is 0", () => {
             const sut = new Power();
   
             const result = sut.calculate(9.876, 0);
   
             expect(result).to.equal(1);
         });
   
         it("should throw when the exponent is not an integer", () => {
             const sut = new Power();
   
             expect(() => sut.calculate(9.876, 1.1)).to.throw(
                 Error,
                 "The exponent must be an integer");
         });
     });
   });

   Running coverage then produces this result (0% for ipower.ts):

   $ npm run coverage
   ...
   -----------|---------|----------|---------|---------|-------------------
   File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
   -----------|---------|----------|---------|---------|-------------------
   All files  |   70.58 |       60 |      50 |   70.58 |
    ipower.ts |       0 |        0 |       0 |       0 | 1-3
    power.ts  |   85.71 |       75 |     100 |   85.71 | 9-10
   -----------|---------|----------|---------|---------|-------------------

   Funny thing I noticed now because I didn't add tests for 100% coverage... if you move the contents of ipower.ts into power.ts the coverage of power.ts is strangely enough higher than before:

   $ npm run coverage
   ...
   ----------|---------|----------|---------|---------|-------------------
   File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
   ----------|---------|----------|---------|---------|-------------------
   All files |    87.5 |       75 |     100 |    87.5 |
    power.ts |    87.5 |       75 |     100 |    87.5 | 7-8
   ----------|---------|----------|---------|---------|-------------------

   👍React with 👍3Reacted by Fabian Meyer, Eric MORAND and Björn Büttner
4. ericmorand commented on Nov 19, 2023

   

   ericmorand

   on Nov 19, 2023

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   Is there news about this issue?
5. jamie-tm commented on Nov 28, 2024

   

   jamie-tm

   on Nov 28, 2024

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   I encounter this too on a regular basis.

   My go-to solution for now is to put my interfaces in one directory and then exclude that whole directory:

   - src/
     - interfaces/
       - widget.ts
     - classes/
       - WidgetFactory.ts
   - test/
     - WidgetFactory.suite.ts
   - .c8rc.yaml
   

   {
     "all": true,
     "src": "./src",
     "exclude": [
       "interfaces/"
     ]
   }

   Or, if you prefer to co-locate your tests and interfaces, you could use file extensions:

   - src/
     - widgets/
       - widget.interface.ts
       - WidgetFactory.spec.ts
       - WidgetFactory.ts
   - .c8rc.yaml
   

   {
     "all": true,
     "src": "./src",
     "exclude": [
       "**/*.interface.ts",
       "**/*.spec.ts"
     ]
   }

   However, both of these share the problem that it's possible to end up with uncovered code if someone accidentally (or intentionally) puts something other than an interface in that directory/file. So, I'd love to see a solution that could somehow recognize and ignore these files automatically.
6. ericmorand commented on Nov 29, 2024

   

   ericmorand

   on Nov 29, 2024

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   @jftanner could please give One Double Zero a try?

   https://www.npmjs.com/package/one-double-zero?activeTab=readme
7. jamie-tm commented on Nov 29, 2024

   

   jamie-tm

   on Nov 29, 2024

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   @jftanner could please give One Double Zero a try?

   No offense, but I'm not interested in switching to such a new tool. A large part of security in open source comes from having many eyes looking at it. At 11 downloads per week, your tool isn't there yet.

   👍React with 👍1Reacted by Fares Azzabi
8. ericmorand commented on Nov 29, 2024

   

   ericmorand

   on Nov 29, 2024

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   That makes no sense right? How can a tool get downloads if you don't download it because it doesn't have downloads.

   It solves your issue. It is fully tested. It is open source. What you want more?