Add --max-warnings flag to tsdx lint (#858)

Works the same as ESLint's --max-warnings flag

If `tsdx lint` finds no errors but more than `--max-warnings`
number of warnings, it exits with a non-zero code. Otherwise,
it exits with 0

- Add lint warning tests for this
- Use default value of Infinity for --max-warnings flag
- Update README's API Reference with new flag

README.md

@@ -502,6 +502,7 @@ Usage
 Options
   --fix               Fixes fixable errors and warnings
   --ignore-pattern    Ignore a pattern
+  --max-warnings      Exits with non-zero error code if number of warnings exceed this number  (default Infinity)
   --write-file        Write the config file locally
   --report-file       Write JSON report to file locally
   -h, --help          Displays this message
@@ -510,6 +511,7 @@ Examples
   $ tsdx lint src
   $ tsdx lint src --fix
   $ tsdx lint src test --ignore-pattern test/foo.ts
+  $ tsdx lint src test --max-warnings 10
   $ tsdx lint src --write-file
   $ tsdx lint src --report-file report.json
 ```

src/index.ts

@@ -545,6 +545,12 @@ prog
   .example('lint src test --fix')
   .option('--ignore-pattern', 'Ignore a pattern')
   .example('lint src test --ignore-pattern test/foobar.ts')
+  .option(
+    '--max-warnings',
+    'Exits with non-zero error code if number of warnings exceed this number',
+    Infinity
+  )
+  .example('lint src test --max-warnings 10')
   .option('--write-file', 'Write the config file locally')
   .example('lint --write-file')
   .option('--report-file', 'Write JSON report to file locally')
@@ -555,6 +561,7 @@ prog
       'ignore-pattern': string;
       'write-file': boolean;
       'report-file': string;
+      'max-warnings': number;
       _: string[];
     }) => {
       if (opts['_'].length === 0 && !opts['write-file']) {
@@ -597,6 +604,9 @@ prog
       if (report.errorCount) {
         process.exit(1);
       }
+      if (report.warningCount > opts['max-warnings']) {
+        process.exit(1);
+      }
     }
   );
 

test/e2e/fixtures/lint/file-with-lint-warnings.ts

@@ -0,0 +1,5 @@
+// this file should have 3 "unused var" lint warnings
+const unusedVar1 = () => {
+  const unusedVar2 = 'baz';
+  const unusedVar3 = '';
+};

test/e2e/tsdx-lint.test.ts

@@ -43,6 +43,48 @@ describe('tsdx lint', () => {
     expect(output.code).toBe(0);
   });
 
+  it('should succeed linting a ts file with warnings when --max-warnings is not used', () => {
+    const testFile = `${lintDir}/file-with-lint-warnings.ts`;
+    const output = shell.exec(`node dist/index.js lint ${testFile}`);
+    expect(output.code).toBe(0);
+    expect(output.stdout.includes('@typescript-eslint/no-unused-vars')).toBe(
+      true
+    );
+  });
+
+  it('should succeed linting a ts file with fewer warnings than --max-warnings', () => {
+    const testFile = `${lintDir}/file-with-lint-warnings.ts`;
+    const output = shell.exec(
+      `node dist/index.js lint ${testFile} --max-warnings 4`
+    );
+    expect(output.code).toBe(0);
+    expect(output.stdout.includes('@typescript-eslint/no-unused-vars')).toBe(
+      true
+    );
+  });
+
+  it('should succeed linting a ts file with same number of warnings as --max-warnings', () => {
+    const testFile = `${lintDir}/file-with-lint-warnings.ts`;
+    const output = shell.exec(
+      `node dist/index.js lint ${testFile} --max-warnings 3`
+    );
+    expect(output.code).toBe(0);
+    expect(output.stdout.includes('@typescript-eslint/no-unused-vars')).toBe(
+      true
+    );
+  });
+
+  it('should fail to lint a ts file with more warnings than --max-warnings', () => {
+    const testFile = `${lintDir}/file-with-lint-warnings.ts`;
+    const output = shell.exec(
+      `node dist/index.js lint ${testFile} --max-warnings 2`
+    );
+    expect(output.code).toBe(1);
+    expect(output.stdout.includes('@typescript-eslint/no-unused-vars')).toBe(
+      true
+    );
+  });
+
   it('should not lint', () => {
     const output = shell.exec(`node dist/index.js lint`);
     expect(output.code).toBe(1);