Added require-const-for-all-caps option to variable-name (#2936)

src/configs/all.ts

@@ -266,7 +266,7 @@ export const rules = {
     "switch-final-break": true,
     "type-literal-delimiter": true,
     "unnecessary-bind": true,
-    "variable-name": { options: ["ban-keywords", "check-format"] },
+    "variable-name": { options: ["ban-keywords", "check-format", "require-const-for-all-caps"] },
     whitespace: {
         options: [
             "check-branch",

src/rules/variableNameRule.ts

@@ -17,7 +17,7 @@
 
 // tslint:disable object-literal-sort-keys
 
-import { hasModifier } from "tsutils";
+import * as tsutils from "tsutils";
 import * as ts from "typescript";
 
 import * as Lint from "../index";
@@ -41,6 +41,7 @@ const OPTION_LEADING_UNDERSCORE = "allow-leading-underscore";
 const OPTION_TRAILING_UNDERSCORE = "allow-trailing-underscore";
 const OPTION_BAN_KEYWORDS = "ban-keywords";
 const OPTION_CHECK_FORMAT = "check-format";
+const OPTION_REQUIRE_CONT_FOR_ALL_CAPS = "require-const-for-all-caps";
 const OPTION_ALLOW_PASCAL_CASE = "allow-pascal-case";
 const OPTION_ALLOW_SNAKE_CASE = "allow-snake-case";
 
@@ -49,11 +50,12 @@ export class Rule extends Lint.Rules.AbstractRule {
         ruleName: "variable-name",
         description: "Checks variable names for various errors.",
         optionsDescription: Lint.Utils.dedent`
-            Five arguments may be optionally provided:
+            Six arguments may be optionally provided:
 
             * \`"${OPTION_CHECK_FORMAT}"\`: allows only lowerCamelCased or UPPER_CASED variable names
               * \`"${OPTION_LEADING_UNDERSCORE}"\` allows underscores at the beginning (only has an effect if "check-format" specified)
               * \`"${OPTION_TRAILING_UNDERSCORE}"\` allows underscores at the end. (only has an effect if "check-format" specified)
+              * \`"${OPTION_REQUIRE_CONT_FOR_ALL_CAPS}"\`: enforces that all variables with UPPER_CASED names should be \`const\`.
               * \`"${OPTION_ALLOW_PASCAL_CASE}"\` allows PascalCase in addition to lowerCamelCase.
               * \`"${OPTION_ALLOW_SNAKE_CASE}"\` allows snake_case in addition to lowerCamelCase.
             * \`"${OPTION_BAN_KEYWORDS}"\`: disallows the use of certain TypeScript keywords as variable or parameter names.
@@ -72,7 +74,7 @@ export class Rule extends Lint.Rules.AbstractRule {
                 ],
             },
             minLength: 0,
-            maxLength: 5,
+            maxLength: 6,
         },
         optionExamples: [[true, "ban-keywords", "check-format", "allow-leading-underscore"]],
         type: "style",
@@ -81,6 +83,8 @@ export class Rule extends Lint.Rules.AbstractRule {
 
     public static KEYWORD_FAILURE = "variable name clashes with keyword/type";
 
+    public static FAILURE_STRING_CONST = "Only `const` variables may be UPPER_CASE.";
+
     public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
         return this.applyWithFunction(sourceFile, walk, parseOptions(this.ruleArguments));
     }
@@ -91,6 +95,7 @@ interface Options {
     checkFormat: boolean;
     leadingUnderscore: boolean;
     trailingUnderscore: boolean;
+    allCapsForConst: boolean;
     allowPascalCase: boolean;
     allowSnakeCase: boolean;
 }
@@ -102,6 +107,7 @@ function parseOptions(ruleArguments: string[]): Options {
         checkFormat: !banKeywords || hasOption(OPTION_CHECK_FORMAT),
         leadingUnderscore: hasOption(OPTION_LEADING_UNDERSCORE),
         trailingUnderscore: hasOption(OPTION_TRAILING_UNDERSCORE),
+        allCapsForConst: hasOption(OPTION_REQUIRE_CONT_FOR_ALL_CAPS),
         allowPascalCase: hasOption(OPTION_ALLOW_PASCAL_CASE),
         allowSnakeCase: hasOption(OPTION_ALLOW_SNAKE_CASE),
     };
@@ -133,31 +139,37 @@ function walk(ctx: Lint.WalkContext<Options>): void {
 
             case ts.SyntaxKind.VariableStatement:
                 // skip 'declare' keywords
-                if (hasModifier(node.modifiers, ts.SyntaxKind.DeclareKeyword)) {
+                if (tsutils.hasModifier(node.modifiers, ts.SyntaxKind.DeclareKeyword)) {
                     return;
                 }
                 break;
 
             case ts.SyntaxKind.Parameter:
             case ts.SyntaxKind.PropertyDeclaration:
-            case ts.SyntaxKind.VariableDeclaration: {
-                const { name, initializer } = node as
-                    | ts.ParameterDeclaration
-                    | ts.PropertyDeclaration
-                    | ts.VariableDeclaration;
-                if (name.kind === ts.SyntaxKind.Identifier) {
-                    handleVariableNameFormat(name, initializer);
-                    // do not check property declarations for keywords, they are allowed to be keywords
-                    if (node.kind !== ts.SyntaxKind.PropertyDeclaration) {
-                        handleVariableNameKeyword(name);
-                    }
-                }
-            }
+                handleDeclaredVariable(node as ts.ParameterDeclaration | ts.PropertyDeclaration);
+                break;
+
+            case ts.SyntaxKind.VariableDeclaration:
+                handleVariableDeclaration(node as ts.VariableDeclaration);
         }
 
         return ts.forEachChild(node, cb);
     });
 
+    function handleDeclaredVariable(
+        node: ts.ParameterDeclaration | ts.PropertyDeclaration | ts.VariableDeclaration,
+    ): void {
+        const { name, initializer } = node;
+
+        if (name.kind === ts.SyntaxKind.Identifier) {
+            handleVariableNameFormat(name, initializer);
+            // do not check property declarations for keywords, they are allowed to be keywords
+            if (node.kind !== ts.SyntaxKind.PropertyDeclaration) {
+                handleVariableNameKeyword(name);
+            }
+        }
+    }
+
     function handleVariableNameFormat(name: ts.Identifier, initializer?: ts.Expression): void {
         if (!options.checkFormat) {
             return;
@@ -179,6 +191,21 @@ function walk(ctx: Lint.WalkContext<Options>): void {
         }
     }
 
+    function handleVariableDeclaration(node: ts.VariableDeclaration): void {
+        handleDeclaredVariable(node);
+
+        if (!ctx.options.allCapsForConst || tsutils.isBindingPattern(node.name)) {
+            return;
+        }
+
+        const declarationList = node.parent;
+        const text = node.name.text;
+
+        if (isUpperCase(text) && !tsutils.isNodeFlagSet(declarationList, ts.NodeFlags.Const)) {
+            ctx.addFailureAtNode(node, Rule.FAILURE_STRING_CONST);
+        }
+    }
+
     function formatFailure(): string {
         let failureMessage = "variable name must be in lowerCamelCase";
         if (options.allowPascalCase) {

test/rules/variable-name/const-only-for-caps/test.ts.lint

@@ -0,0 +1,38 @@
+var snake_case_var;
+    ~~~~~~~~~~~~~~  [regular-case]
+
+var camelCaseVar;
+
+var PascalCaseVar;
+    ~~~~~~~~~~~~~  [regular-case]
+
+var UPPER_CASE_VAR;
+    ~~~~~~~~~~~~~~  [const]
+
+let snake_case_let;
+    ~~~~~~~~~~~~~~  [regular-case]
+
+let camelCaseLet;
+
+let PascalCaseLet;
+    ~~~~~~~~~~~~~  [regular-case]
+
+let UPPER_CASE_LET;
+    ~~~~~~~~~~~~~~  [const]
+
+const snake_case_const;
+      ~~~~~~~~~~~~~~~~  [regular-case]
+
+const camelCaseConst;
+
+const PascalCaseConst;
+      ~~~~~~~~~~~~~~~  [regular-case]
+
+const UPPER_CASE_CONST;
+
+class Test {
+    public static readonly MY_FIELD = 10;
+}
+
+[const]: Only `const` variables may be UPPER_CASE.
+[regular-case]: variable name must be in lowerCamelCase or UPPER_CASE

test/rules/variable-name/const-only-for-caps/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "variable-name": [true, "require-const-for-all-caps"]
+  }
+}