From c7e2ba898d3c6f103be0a67c268bf49890910b30 Mon Sep 17 00:00:00 2001
From: Bradley Meck Farias <bradley.meck@gmail.com>
Date: Thu, 3 Oct 2024 11:41:08 -0500
Subject: [PATCH] feat: rule no-unsafe-values

Fixes #29
---
 src/rules/no-unsafe-values.js        |  54 ++++++++++++
 tests/rules/no-unsafe-values.test.js | 125 +++++++++++++++++++++++++++
 2 files changed, 179 insertions(+)
 create mode 100644 src/rules/no-unsafe-values.js
 create mode 100644 tests/rules/no-unsafe-values.test.js

diff --git a/src/rules/no-unsafe-values.js b/src/rules/no-unsafe-values.js
new file mode 100644
index 0000000..8fb9686
--- /dev/null
+++ b/src/rules/no-unsafe-values.js
@@ -0,0 +1,54 @@
+/**
+ * @fileoverview Rule to unsafe values in JSON.
+ * @author Bradley Meck Farias
+ */
+
+export default {
+	meta: {
+		type: "problem",
+
+		docs: {
+			description: "Disallow JSON values that are unsafe for interchange",
+		},
+
+		messages: {
+			unsafeNumber: "Number outside safe range found.",
+			loneSurrogate: "Lone surrogate found.",
+		},
+	},
+
+	create(context) {
+		return {
+			Number(node) {
+				if (Number.isFinite(node.value) !== true) {
+					context.report({
+						loc: node.loc,
+						messageId: "unsafeNumber",
+					});
+				}
+			},
+			String(node) {
+				if (node.value.isWellFormed) {
+					if (node.value.isWellFormed()) {
+						return;
+					}
+				}
+				// match any high surrogate and, if it exists, a paired low surrogate
+				// match any low surrogate not already matched
+				const surrogatePattern =
+					/[\uD800-\uDBFF][\uDC00-\uDFFF]?|[\uDC00-\uDFFF]/gu;
+				let match = surrogatePattern.exec(node.value);
+				while (match) {
+					// only need to report non-paired surrogates
+					if (match[0].length < 2) {
+						context.report({
+							loc: node.loc,
+							messageId: "loneSurrogate",
+						});
+					}
+					match = surrogatePattern.exec(node.value);
+				}
+			},
+		};
+	},
+};
diff --git a/tests/rules/no-unsafe-values.test.js b/tests/rules/no-unsafe-values.test.js
new file mode 100644
index 0000000..2052b8f
--- /dev/null
+++ b/tests/rules/no-unsafe-values.test.js
@@ -0,0 +1,125 @@
+/**
+ * @fileoverview Tests for no-empty-keys rule.
+ * @author Bradley Meck Farias
+ */
+
+//------------------------------------------------------------------------------
+// Imports
+//------------------------------------------------------------------------------
+
+import rule from "../../src/rules/no-unsafe-values.js";
+import json from "../../src/index.js";
+import { RuleTester } from "eslint";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+	plugins: {
+		json,
+	},
+	language: "json/json",
+});
+
+ruleTester.run("no-unsafe-values", rule, {
+	valid: [
+		"123",
+		{
+			code: "1234",
+			language: "json/json5",
+		},
+		{
+			code: "12345",
+			language: "json/json5",
+		},
+		'"🔥"',
+		'"\\ud83d\\udd25"',
+	],
+	invalid: [
+		{
+			code: "2e308",
+			errors: [
+				{
+					messageId: "unsafeNumber",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 6,
+				},
+			],
+		},
+		{
+			code: "-2e308",
+			errors: [
+				{
+					messageId: "unsafeNumber",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 7,
+				},
+			],
+		},
+		{
+			code: '"\ud83d"',
+			errors: [
+				{
+					messageId: "loneSurrogate",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 4,
+				},
+			],
+		},
+		{
+			code: '"\\ud83d"',
+			errors: [
+				{
+					messageId: "loneSurrogate",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 9,
+				},
+			],
+		},
+		{
+			code: '"\udd25"',
+			errors: [
+				{
+					messageId: "loneSurrogate",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 4,
+				},
+			],
+		},
+		{
+			code: '"\\udd25"',
+			errors: [
+				{
+					messageId: "loneSurrogate",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 9,
+				},
+			],
+		},
+		{
+			code: '"\ud83d\ud83d"',
+			errors: [
+				{
+					messageId: "loneSurrogate",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 5,
+				},
+			],
+		},
+	],
+});