feat: Support warnings-as-errors

This patch adds support for using --warnings-as-errors as a parameter
for the lint command.

This complements the PR mozilla/addons-linter#1016
and completes the issue mozilla/addons-linter#1014.

src/cmd/lint.js

@@ -16,6 +16,7 @@ export type LinterCreatorParams = {
     logLevel: 'debug' | 'fatal',
     stack: boolean,
     pretty?: boolean,
+    warningsAsErrors?: boolean,
     metadata?: boolean,
     output?: LinterOutputType,
     boring?: boolean,
@@ -42,6 +43,7 @@ export type LintCmdParams = {
   output?: LinterOutputType,
   metadata?: boolean,
   pretty?: boolean,
+  warningsAsErrors?: boolean,
 };
 
 export type LintCmdOptions = {
@@ -52,7 +54,7 @@ export type LintCmdOptions = {
 export default function lint(
   {
     verbose, sourceDir, selfHosted, boring, output,
-    metadata, pretty,
+    metadata, pretty, warningsAsErrors,
   }: LintCmdParams,
   {
     createLinter = defaultLinterCreator,
@@ -65,6 +67,7 @@ export default function lint(
       logLevel: verbose ? 'debug' : 'fatal',
       stack: Boolean(verbose),
       pretty,
+      warningsAsErrors,
       metadata,
       output,
       boring,

src/program.js

@@ -297,6 +297,12 @@ Example: $0 --help run.
         type: 'boolean',
         default: false,
       },
+      'warnings-as-errors': {
+        describe: 'Treat warnings as errors',
+        alias: 'w',
+        type: 'boolean',
+        default: false,
+      },
       'pretty': {
         describe: 'Prettify JSON output',
         type: 'boolean',

tests/unit/test-cmd/test.lint.js

@@ -65,6 +65,22 @@ describe('lint', () => {
     });
   });
 
+  it('passes warningsAsErrors to the linter', () => {
+    const {lint, createLinter} = setUp();
+    return lint({warningsAsErrors: true}).then(() => {
+      const config = createLinter.firstCall.args[0].config;
+      assert.equal(config.warningsAsErrors, true);
+    });
+  });
+
+  it('passes warningsAsErrors undefined to the linter', () => {
+    const {lint, createLinter} = setUp();
+    return lint({}).then(() => {
+      const config = createLinter.firstCall.args[0].config;
+      assert.equal(config.warningsAsErrors, undefined);
+    });
+  });
+
   it('configures the linter when verbose', () => {
     const {lint, createLinter} = setUp();
     return lint({verbose: true}).then(() => {