Fix syntax highlighting for .class files

core/util/index.test.ts

@@ -207,7 +207,7 @@ World
 
   it("should handle strings with only whitespace", () => {
     const result = dedent`
-    
+
     `;
     expect(result).toBe("");
   });
@@ -249,9 +249,9 @@ World
 
   it("should handle a string with only one non-empty line", () => {
     const result = dedent`
-      
+
       Hello World!
-      
+
     `;
     expect(result).toBe("Hello World!");
   });
@@ -373,11 +373,16 @@ describe("getMarkdownLanguageTagForFile", () => {
     expect(getMarkdownLanguageTagForFile("test.py")).toBe("python");
     expect(getMarkdownLanguageTagForFile("test.tsx")).toBe("tsx");
     expect(getMarkdownLanguageTagForFile("test.java")).toBe("java");
+    expect(getMarkdownLanguageTagForFile("test.class")).toBe("java");
     expect(getMarkdownLanguageTagForFile("test.md")).toBe("markdown");
     expect(getMarkdownLanguageTagForFile("test.sh")).toBe("shell");
     expect(getMarkdownLanguageTagForFile("test.sql")).toBe("sql");
   });
 
+  it("should sanitize ranges from the extension", () => {
+    expect(getMarkdownLanguageTagForFile("test.java (1-5)")).toBe("java");
+  });
+
   it("should return the extension if not in the known list", () => {
     expect(getMarkdownLanguageTagForFile("file.unknownext")).toBe("unknownext");
   });

core/util/index.ts

@@ -74,6 +74,7 @@ export function getMarkdownLanguageTagForFile(filepath: string): string {
     tsx: "tsx",
     ts: "typescript",
     java: "java",
+    class:"java", //.class files decompile to Java
     go: "go",
     rb: "ruby",
     rs: "rust",
@@ -96,17 +97,28 @@ export function getMarkdownLanguageTagForFile(filepath: string): string {
     ps1: "powershell",
   };
 
-  const ext = filepath.split(".").pop();
+  const ext = sanitizeExtension(filepath.split(".").pop());
   return ext ? (extToLangMap[ext] ?? ext) : "";
 }
 
+
+function sanitizeExtension(ext?: string): string|undefined {
+  if (ext) {
+    //ignore ranges in extension eg. "java (11-23)"
+    const match = ext.match(/^(\S+)\s*(\(.*\))?$/);
+    if (match) {
+      ext = match[1];
+    }
+  }
+  return ext;
+}
+
 export function copyOf(obj: any): any {
   if (obj === null || obj === undefined) {
     return obj;
   }
   return JSON.parse(JSON.stringify(obj));
 }
-``;
 
 export function deduplicateArray<T>(
   array: T[],