Add no-inline-assertions rule

docs/rules/no-inline-assertions.md

@@ -0,0 +1,33 @@
+# Ensure no assertions are called from inline functions
+
+Prevent assertions being called from an inline function, to make it clear that it does not return.
+
+## Fail
+```js
+import test from 'ava';
+
+test('foo', t => t.true(fn()));
+```
+
+```js
+import test from 'ava';
+
+test('foo', t => { t.true(fn()) });
+```
+
+```js
+import test from 'ava';
+
+test('foo', t =>
+	t.true(fn())
+);
+```
+
+## Pass
+```js
+import test from 'ava';
+
+test('foo', t => {
+	t.true(fn())
+});
+```

index.js

@@ -28,6 +28,7 @@ module.exports = {
 				'ava/no-identical-title': 'error',
 				'ava/no-ignored-test-files': 'error',
 				'ava/no-import-test-files': 'error',
+				'ava/no-inline-assertions': 'error',
 				'ava/no-invalid-end': 'error',
 				'ava/no-nested-tests': 'error',
 				'ava/no-only-test': 'error',

readme.md

@@ -46,6 +46,7 @@ Configure it in `package.json`.
 			"ava/no-identical-title": "error",
 			"ava/no-ignored-test-files": "error",
 			"ava/no-import-test-files": "error",
+			"ava/no-inline-assertions": "error",
 			"ava/no-invalid-end": "error",
 			"ava/no-nested-tests": "error",
 			"ava/no-only-test": "error",
@@ -83,6 +84,7 @@ The rules will only activate in test files.
 - [no-identical-title](docs/rules/no-identical-title.md) - Ensure no tests have the same title.
 - [no-ignored-test-files](docs/rules/no-ignored-test-files.md) - Ensure no tests are written in ignored files.
 - [no-import-test-files](docs/rules/no-import-test-files.md) - Ensure no test files are imported anywhere.
+- [no-inline-assertions](docs/rules/no-inline-assertions.md) - Ensure no assertions are called from inline functions.
 - [no-invalid-end](docs/rules/no-invalid-end.md) - Ensure `t.end()` is only called inside `test.cb()`.
 - [no-nested-tests](docs/rules/no-nested-tests.md) - Ensure no tests are nested.
 - [no-only-test](docs/rules/no-only-test.md) - Ensure no `test.only()` are present. *(fixable)*

rules/no-inline-assertions.js

@@ -0,0 +1,61 @@
+'use strict';
+const {visitIf} = require('enhance-visitors');
+const createAvaRule = require('../create-ava-rule');
+const util = require('../util');
+
+function report({node, context}) {
+	context.report({
+		node,
+		message: 'Assertions should not be called from an inline function.'
+	});
+}
+
+const create = context => {
+	const ava = createAvaRule();
+
+	return ava.merge({
+		CallExpression: visitIf([
+			ava.isInTestFile,
+			ava.isTestNode
+		])(node => {
+			const functionArgIndex = node.arguments.length - 1;
+			if (functionArgIndex > 1) {
+				return;
+			}
+
+			const functionArg = node.arguments[functionArgIndex];
+
+			if (!util.isFunctionExpression(functionArg)) {
+				return;
+			}
+
+			const {body} = functionArg;
+			if (body.type === 'CallExpression') {
+				report({node, context});
+				return;
+			}
+
+			if (body.type === 'BlockStatement') {
+				if (body.loc.start.line !== body.loc.end.line) {
+					return;
+				}
+
+				if (body.body.length === 0) {
+					return;
+				}
+
+				report({node, context});
+			}
+		})
+	});
+};
+
+module.exports = {
+	create,
+	meta: {
+		docs: {
+			url: util.getDocsUrl(__filename)
+		},
+		type: 'suggestion'
+	}
+};

test/no-inline-assertions.js

@@ -0,0 +1,58 @@
+import test from 'ava';
+import avaRuleTester from 'eslint-ava-rule-tester';
+import rule from '../rules/no-inline-assertions';
+
+const ruleTester = avaRuleTester(test, {
+	env: {
+		es6: true
+	}
+});
+
+const errors = [{ruleId: 'no-inline-assertions'}];
+const header = 'const test = require(\'ava\');\n';
+
+ruleTester.run('no-todo-test', rule, {
+	valid: [
+		header + 'test("my test name", t => {\n t.true(fn()); \n});',
+		// Shouldn't be triggered since test body is empty
+		header + 'test("my test name", () => {});',
+		header + 'test("my test name", (t) => {});',
+		// Shouldn't be triggered since test body is ill-defined
+		header + 'test("my test name", (t) => "foo");',
+		// Shouldn't be triggered since it's not a test file
+		'test.todo("my test name");',
+		// Shouldn't be triggered since the signature is incorrect
+		header + 'test.todo("my test name", "bar");',
+		header + 'test.todo("my test name", undefined, t => {})'
+	],
+	invalid: [
+		{
+			code: header + 'test("my test name", t => { t.skip(); });',
+			errors
+		},
+		{
+			code: header + 'test("my test name", t => t.skip());',
+			errors
+		},
+		{
+			code: header + 'test("my test name", t => t.true(fn()));',
+			errors
+		},
+		{
+			code: header + 'test("my test name", t => \n t.true(fn()));',
+			errors
+		},
+		{
+			code: header + 'test("my test name", t => { t.true(fn()) });',
+			errors
+		},
+		{
+			code: header + 'test("my test name", function(t) { foo(); });',
+			errors
+		},
+		{
+			code: header + 'test("my test name", t => { return t.true(fn()) });',
+			errors
+		}
+	]
+});