Improve error messages in jsonc/valid-json-number rule (#40)

Author: ota-meshi

lib/rules/valid-json-number.ts

@@ -1,3 +1,4 @@
+import type { Rule } from "eslint"
 import type { AST } from "jsonc-eslint-parser"
 import { isNumberIdentifier } from "jsonc-eslint-parser"
 import type { RuleListener } from "../types"
@@ -7,9 +8,6 @@ import { createRule } from "../utils"
  * Checks if the given string is valid number as JSON.
  */
 function isValidNumber(text: string): boolean {
-    if (text.startsWith(".") || text.endsWith(".")) {
-        return false
-    }
     try {
         JSON.parse(text)
     } catch {
@@ -32,6 +30,13 @@ export default createRule("valid-json-number", {
             invalidSpace: "Spaces after minus sign are not allowed in JSON.",
             invalidPlus: "Plus signs are not allowed in JSON.",
             invalidIdentifier: "`{{name}}` are not allowed in JSON.",
+            invalidLeadingDecimalPoint:
+                "Leading decimal point is not allowed in JSON.",
+            invalidTrailingDecimalPoint:
+                "Trailing decimal point is not allowed in JSON.",
+            invalidHex: "Hexadecimal literals are not allowed in JSON.",
+            invalidOctal: "Octal literals are not allowed in JSON.",
+            invalidBinary: "Binary literals are not allowed in JSON.",
         },
         type: "problem",
     },
@@ -83,17 +88,52 @@ export default createRule("valid-json-number", {
                     return
                 }
                 const text = sourceCode.text.slice(...node.range)
-                if (!isValidNumber(text)) {
+
+                if (text.startsWith(".")) {
                     context.report({
                         loc: node.loc,
-                        messageId: "invalid",
+                        messageId: "invalidLeadingDecimalPoint",
                         fix(fixer) {
-                            return fixer.replaceTextRange(
-                                node.range,
-                                `${node.value}`,
-                            )
+                            return fixer.insertTextBeforeRange(node.range, "0")
                         },
                     })
+                    return
+                }
+                if (text.endsWith(".")) {
+                    context.report({
+                        loc: node.loc,
+                        messageId: "invalidTrailingDecimalPoint",
+                        fix(fixer) {
+                            return fixer.removeRange([
+                                node.range[1] - 1,
+                                node.range[1],
+                            ])
+                        },
+                    })
+                    return
+                }
+                if (
+                    text.startsWith("0x") ||
+                    text.startsWith("0o") ||
+                    text.startsWith("0b")
+                ) {
+                    context.report({
+                        loc: node.loc,
+                        messageId: text.startsWith("0x")
+                            ? "invalidHex"
+                            : text.startsWith("0o")
+                            ? "invalidOctal"
+                            : "invalidBinary",
+                        fix: buildFix(node),
+                    })
+                    return
+                }
+                if (!isValidNumber(text)) {
+                    context.report({
+                        loc: node.loc,
+                        messageId: "invalid",
+                        fix: buildFix(node),
+                    })
                 }
             },
             JSONIdentifier(node: AST.JSONIdentifier) {
@@ -109,5 +149,16 @@ export default createRule("valid-json-number", {
                 })
             },
         }
+
+        /**
+         * Build fixer for number
+         */
+        function buildFix(
+            node: AST.JSONLiteral,
+        ): (fixer: Rule.RuleFixer) => Rule.Fix {
+            return (fixer) => {
+                return fixer.replaceTextRange(node.range, `${node.value}`)
+            }
+        }
     },
 })

tests/lib/rules/valid-json-number.ts

@@ -3,6 +3,9 @@ import rule from "../../../lib/rules/valid-json-number"
 
 const tester = new RuleTester({
     parser: require.resolve("jsonc-eslint-parser"),
+    parserOptions: {
+        ecmaVersion: 2020,
+    },
 })
 
 tester.run("valid-json-number", rule as any, {
@@ -22,7 +25,7 @@ tester.run("valid-json-number", rule as any, {
             output: "[0.4, 42]",
             errors: [
                 {
-                    message: "Invalid number for JSON.",
+                    message: "Leading decimal point is not allowed in JSON.",
                     line: 1,
                     column: 2,
                     endLine: 1,
@@ -40,7 +43,7 @@ tester.run("valid-json-number", rule as any, {
         {
             code: "123.",
             output: "123",
-            errors: ["Invalid number for JSON."],
+            errors: ["Trailing decimal point is not allowed in JSON."],
         },
         {
             filename: "test.json5",
@@ -114,19 +117,48 @@ tester.run("valid-json-number", rule as any, {
             output: "291",
             errors: [
                 {
-                    message: "Invalid number for JSON.",
+                    message: "Hexadecimal literals are not allowed in JSON.",
                     line: 1,
                     column: 1,
                     endColumn: 6,
                 },
             ],
         },
+        {
+            code: "[-0x123, +0x123]",
+            output: "[-291, 0x123]",
+            errors: [
+                "Hexadecimal literals are not allowed in JSON.",
+                "Plus signs are not allowed in JSON.",
+                "Hexadecimal literals are not allowed in JSON.",
+            ],
+        },
+        {
+            code: "[0o123,-0o123,+0o123]",
+            output: "[83,-83,0o123]",
+            errors: [
+                "Octal literals are not allowed in JSON.",
+                "Octal literals are not allowed in JSON.",
+                "Plus signs are not allowed in JSON.",
+                "Octal literals are not allowed in JSON.",
+            ],
+        },
+        {
+            code: "[0b1001,-0b1001,+0b1001]",
+            output: "[9,-9,0b1001]",
+            errors: [
+                "Binary literals are not allowed in JSON.",
+                "Binary literals are not allowed in JSON.",
+                "Plus signs are not allowed in JSON.",
+                "Binary literals are not allowed in JSON.",
+            ],
+        },
         {
             filename: "test.vue",
             code: `<custom-block lang="json">0x123</custom-block>`,
             output: `<custom-block lang="json">291</custom-block>`,
             parser: require.resolve("vue-eslint-parser"),
-            errors: ["Invalid number for JSON."],
+            errors: ["Hexadecimal literals are not allowed in JSON."],
         },
     ],
 })