fix: support for Japanese slash date without year (#16)

Author: watackeech

src/textlint-rule-date-weekday-mismatch.js

@@ -58,10 +58,6 @@ const detectLang = (tags, preferLang) => {
  * @returns {string}
  */
 const addYearToDateText = (dateText, year, lang) => {
-    // Japanese: 4月23日(月) → 2024年4月23日(月)
-    if (lang === "ja") {
-        return `${year}年${dateText}`;
-    }
     // Slash: 4/23(月) → 2024/4/23(月)
     if (/^[0-9]{1,2}\/[0-9]{1,2}/.test(dateText)) {
         return `${year}/${dateText}`;
@@ -70,6 +66,10 @@ const addYearToDateText = (dateText, year, lang) => {
     if (/^[0-9]{1,2}-[0-9]{1,2}/.test(dateText)) {
         return `${year}-${dateText}`;
     }
+    // Japanese: 4月23日(月) → 2024年4月23日(月)
+    if (lang === "ja") {
+        return `${year}年${dateText}`;
+    }
     // Default: prepend year and a space
     return `${year} ${dateText}`;
 }

test/textlint-rule-date-weekday-mismatch-test.js

@@ -31,6 +31,11 @@ tester.run("rule", rule, {
             options: { useCurrentYearIfMissing: true, currentYear: 2025, lang: "en" },
             // 2025-04-23 is Wednesday
         },
+        {
+            text: "6/20(金)",
+            options: { useCurrentYearIfMissing: true, currentYear: 2025, lang: "ja" },
+            // 2025/06/20は金曜日
+        },
     ],
     invalid: [
         // single match
@@ -159,5 +164,17 @@ tester.run("rule", rule, {
                 }
             ]
         },
+        {
+            text: "6/20(木)",
+            output: "6/20(金)",
+            options: { useCurrentYearIfMissing: true, currentYear: 2025, lang: "ja" },
+            errors: [
+                {
+                    message: "6/20(木) mismatch weekday.\n6/20(木) => 6/20(金)",
+                    line: 1,
+                    column: 6
+                }
+            ]
+        },
     ]
 });