eslint/tests/lib/rules/no-unused-expressions.js

   1 /**
   2  * @fileoverview Tests for no-unused-expressions rule.
   3  * @author Michael Ficarra
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const rule = require("../../../lib/rules/no-unused-expressions"),
  13     { RuleTester } = require("../../../lib/rule-tester");
  14
  15 //------------------------------------------------------------------------------
  16 // Tests
  17 //------------------------------------------------------------------------------
  18
  19 const ruleTester = new RuleTester();
  20
  21 ruleTester.run("no-unused-expressions", rule, {
  22     valid: [
  23         "function f(){}",
  24         "a = b",
  25         "new a",
  26         "{}",
  27         "f(); g()",
  28         "i++",
  29         "a()",
  30         { code: "a && a()", options: [{ allowShortCircuit: true }] },
  31         { code: "a() || (b = c)", options: [{ allowShortCircuit: true }] },
  32         { code: "a ? b() : c()", options: [{ allowTernary: true }] },
  33         { code: "a ? b() || (c = d) : e()", options: [{ allowShortCircuit: true, allowTernary: true }] },
  34         "delete foo.bar",
  35         "void new C",
  36         "\"use strict\";",
  37         "\"directive one\"; \"directive two\"; f();",
  38         "function foo() {\"use strict\"; return true; }",
  39         { code: "var foo = () => {\"use strict\"; return true; }", parserOptions: { ecmaVersion: 6 } },
  40         "function foo() {\"directive one\"; \"directive two\"; f(); }",
  41         "function foo() { var foo = \"use strict\"; return true; }",
  42         {
  43             code: "function* foo(){ yield 0; }",
  44             parserOptions: { ecmaVersion: 6 }
  45         },
  46         {
  47             code: "async function foo() { await 5; }",
  48             parserOptions: { ecmaVersion: 8 }
  49         },
  50         {
  51             code: "async function foo() { await foo.bar; }",
  52             parserOptions: { ecmaVersion: 8 }
  53         },
  54         {
  55             code: "async function foo() { bar && await baz; }",
  56             options: [{ allowShortCircuit: true }],
  57             parserOptions: { ecmaVersion: 8 }
  58         },
  59         {
  60             code: "async function foo() { foo ? await bar : await baz; }",
  61             options: [{ allowTernary: true }],
  62             parserOptions: { ecmaVersion: 8 }
  63         },
  64         {
  65             code: "tag`tagged template literal`",
  66             options: [{ allowTaggedTemplates: true }],
  67             parserOptions: { ecmaVersion: 6 }
  68         },
  69         {
  70             code: "shouldNotBeAffectedByAllowTemplateTagsOption()",
  71             options: [{ allowTaggedTemplates: true }],
  72             parserOptions: { ecmaVersion: 6 }
  73         }
  74     ],
  75     invalid: [
  76         { code: "0", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  77         { code: "a", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  78         { code: "f(), 0", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  79         { code: "{0}", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  80         { code: "[]", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  81         { code: "a && b();", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  82         { code: "a() || false", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  83         { code: "a || (b = c)", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  84         { code: "a ? b() || (c = d) : e", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  85         {
  86             code: "`untagged template literal`",
  87             parserOptions: { ecmaVersion: 6 },
  88             errors: [{ messageId: "unusedExpression" }]
  89         },
  90         {
  91             code: "tag`tagged template literal`",
  92             parserOptions: { ecmaVersion: 6 },
  93             errors: [{ messageId: "unusedExpression" }]
  94         },
  95         { code: "a && b()", options: [{ allowTernary: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  96         { code: "a ? b() : c()", options: [{ allowShortCircuit: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  97         { code: "a || b", options: [{ allowShortCircuit: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  98         { code: "a() && b", options: [{ allowShortCircuit: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
  99         { code: "a ? b : 0", options: [{ allowTernary: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 100         { code: "a ? b : c()", options: [{ allowTernary: true }], errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 101         { code: "foo.bar;", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 102         { code: "!a", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 103         { code: "+a", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 104         { code: "\"directive one\"; f(); \"directive two\";", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 105         { code: "function foo() {\"directive one\"; f(); \"directive two\"; }", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 106         { code: "if (0) { \"not a directive\"; f(); }", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 107         { code: "function foo() { var foo = true; \"use strict\"; }", errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 108         { code: "var foo = () => { var foo = true; \"use strict\"; }", parserOptions: { ecmaVersion: 6 }, errors: [{ messageId: "unusedExpression", type: "ExpressionStatement" }] },
 109         {
 110             code: "`untagged template literal`",
 111             options: [{ allowTaggedTemplates: true }],
 112             parserOptions: { ecmaVersion: 6 },
 113             errors: [{ messageId: "unusedExpression" }]
 114         },
 115         {
 116             code: "`untagged template literal`",
 117             options: [{ allowTaggedTemplates: false }],
 118             parserOptions: { ecmaVersion: 6 },
 119             errors: [{ messageId: "unusedExpression" }]
 120         },
 121         {
 122             code: "tag`tagged template literal`",
 123             options: [{ allowTaggedTemplates: false }],
 124             parserOptions: { ecmaVersion: 6 },
 125             errors: [{ messageId: "unusedExpression" }]
 126         }
 127     ]
 128 });