rule prevent-errortype

docs/rules/prevent-errortype.md

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+# Prevent specifying error type in `t.notThrows()`
+
+AVA will fail if error type is specified with `t.notThrows()`.
+
+
+## Fail
+
+```js
+const test = require('ava');
+
+test('some test', t => {
+    t.notThrows(() => {
+        t.pass();
+    }, TypeError);
+});
+```
+
+
+## Pass
+
+```js
+const test = require('ava');
+
+test('some test', t => {
+    t.notThrows(() => {
+        t.pass();
+    });
+});
+
+test('some test', t => {
+    t.throws(() => {
+        t.pass();
+    }, TypeError);
+});
+```

rules/prevent-errortype.js

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+'use strict';
+const {visitIf} = require('enhance-visitors');
+const util = require('../util');
+const createAvaRule = require('../create-ava-rule');
+
+const nameRegexp = /^(?:[A-Z][a-z0-9]*)*Error$/;
+
+const create = context => {
+	const ava = createAvaRule();
+
+	return ava.merge({
+		CallExpression: visitIf([
+			ava.isInTestFile,
+			ava.isInTestNode
+		])(node => {
+			const functionArgIndex = node.arguments.length - 1;
+			let functionArgName;
+
+			if (typeof node.callee.property === 'undefined') {
+				return;
+			}
+
+			const calleeProperty = node.callee.property.name;
+
+			if (functionArgIndex === 1) {
+				functionArgName = node.arguments[1].name;
+			} else {
+				return;
+			}
+
+			if (calleeProperty === 'notThrows') {
+				if (nameRegexp.test(functionArgName)) {
+					context.report({
+						node,
+						message: 'Do not specify Error in t.notThrows()'
+					});
+				}
+			}
+		})
+	});
+};
+
+module.exports = {
+	create,
+	meta: {
+		docs: {
+			url: util.getDocsUrl(__filename)
+		}
+	}
+};

test/prevent-errortype.js

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+import test from 'ava';
+import avaRuleTester from 'eslint-ava-rule-tester';
+import rule from '../rules/prevent-errortype';
+
+const ruleTester = avaRuleTester(test, {
+	env: {
+		es6: true
+	}
+});
+
+const errors = [{ruleId: 'prevent-errortype'}];
+
+const header = 'const test = require(\'ava\');\n';
+
+ruleTester.run('prevent-errortype', rule, {
+	valid: [
+		header + 'test(\'some test\',t => {t.notThrows(() => {t.pass();});});',
+		header + 'test(t => {t.notThrows(() => {t.pass();});});',
+		header + 'test(t => {t.throws(() => {t.pass();}, TypeError);});',
+		header + 'test(t => {t.end(); });'
+	],
+	invalid: [
+		{
+			code: header + 'test(t => {t.notThrows(() => {t.pass();}, TypeError);});',
+			errors
+		},
+		{
+			code: header + 'test(\'some test\',t => {t.notThrows(() => {t.pass();}, TypeError);});',
+			errors
+		}
+	]
+});