added errors helper

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.2.0 / 2017-10-28
+
+* added `errors` helper
+
 ## 0.1.0 / 2017-10-26
 
 * updated TypeScript target to ES2017

README.md

@@ -34,6 +34,12 @@ If there are type errors, an error will be thrown indicating the position of the
 Error: /absolute/path/to/filename.js (Ln 5, Col 6): Argument of type '123' is not assignable to parameter of type 'string'
 ```
 
+Also, in case errors are expected, we can test using the following assertions indicating the number of errors expected:
+
+```javascript
+expect('/absolute/path/to/filename.js').to.have.types.errors(1);
+```
+
 ## Disclaimer
 
 The plugin is in experimental phase. Use it gently and provide feedback! :)

lib/index.js

@@ -15,19 +15,23 @@ const prettifyDiagnostic = (diagnostic) => {
   const messageText = ts.flattenDiagnosticMessageText(diagnostic.messageText, '\n');
 
   return `${diagnostic.file.fileName} (Ln ${line + 1}, Col ${character + 1}): ${messageText}`
-}
+};
 
 module.exports = (chai, utils) => {
   const Assertion = chai.Assertion;
 
-  utils.addProperty(Assertion.prototype, 'types');
-
-  utils.addChainableMethod(Assertion.prototype, 'validated', function () {
-    const filename = utils.flag(this, 'object');
+  const getObjectDiagnostics = (target) => {
+    const filename = utils.flag(target, 'object');
     const program = ts.createProgram([filename], options);
     const results = program.emit();
 
-    const diagnostics = ts.getPreEmitDiagnostics(program).concat(results.diagnostics);
+    return ts.getPreEmitDiagnostics(program).concat(results.diagnostics);
+  };
+
+  utils.addProperty(Assertion.prototype, 'types');
+
+  utils.addChainableMethod(Assertion.prototype, 'validated', function () {
+    const diagnostics = getObjectDiagnostics(this);
 
     try {
       new chai.Assertion(diagnostics).to.have.length(0);
@@ -39,4 +43,16 @@ module.exports = (chai, utils) => {
   }, function () {
     utils.flag(this, 'types.validated', true);
   });
+
+  utils.addChainableMethod(Assertion.prototype, 'errors', function (expectedErrors) {
+    const diagnostics = getObjectDiagnostics(this);
+
+    if (expectedErrors) {
+      new chai.Assertion(diagnostics).to.have.length(expectedErrors);
+    } else {
+      new chai.Assertion(diagnostics).to.have.length.above(0);
+    }
+  }, function () {
+    utils.flag(this, 'types.errors', true);
+  })
 };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "chai-as-typed",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Chai assertions for types defined via JSDoc",
   "main": "lib/index.js",
   "scripts": {

test/index.js

@@ -4,22 +4,42 @@ const expect = chai.expect;
 
 chai.use(chaiAsTyped);
 
-describe('Types validation', function () {
-  it('should succeed with correct types', function () {
-    this.timeout(5000);
+describe('types', function () {
+  context('validated', function () {
+    it('should succeed with correct types', function () {
+      this.timeout(5000);
 
-    const filename = __dirname + '/fixture/valid.js';
+      const filename = __dirname + '/fixture/valid.js';
 
-    expect(filename).to.have.types.validated();
+      expect(filename).to.have.types.validated();
+    });
+
+    it('should fail with wrong types', function () {
+      this.timeout(5000);
+
+      const filename = __dirname + '/fixture/invalid.js';
+
+      try {
+        expect(filename).to.have.types.validated();
+      } catch (error) {}
+    });
   });
 
-  it('should fail with wrong types', function () {
-    this.timeout(5000);
+  context('errors', function () {
+    it('should have expected number of errors', function () {
+      this.timeout(5000);
 
-    const filename = __dirname + '/fixture/invalid.js';
+      const filename = __dirname + '/fixture/invalid.js';
 
-    try {
-      expect(filename).to.have.types.validated();
-    } catch (error) {}
+      expect(filename).to.have.types.errors(1);
+    });
+
+    it('should have unspecified number of errors', function () {
+      this.timeout(5000);
+
+      const filename = __dirname + '/fixture/invalid.js';
+
+      expect(filename).to.have.types.errors();
+    });
   });
 });