[typespec-vscode] Fix issue when the 'entrypoint' setting is default to null

.chronus/changes/fix-entrypoint-setting-is-null-2025-8-19-7-48-25.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Fix issue when the 'entrypoint' setting is default to null

packages/compiler/src/utils/misc.ts

@@ -37,6 +37,10 @@ export function deepClone<T>(value: T): T {
     return value.map(deepClone) as any;
   }
 
+  if (value === null) {
+    return value;
+  }
+
   if (typeof value === "object") {
     const obj: any = {};
     for (const prop in value) {

packages/compiler/test/server/entrypoint-resolver.test.ts

@@ -99,37 +99,60 @@ it("falls back to tspMain from package.json when no client entrypoints exist", a
   expect(result).toBe(expected);
 });
 
-it("falls back to default main.tsp when no client entrypoints and no tspMain in package.json", async () => {
+it("uses the given path as main when nothing else is found", async () => {
   const host = createMockHost();
-  const dir = "/lib";
-  const filePath = joinPaths(dir, "src", "index.tsp");
-  const expected = joinPaths(dir, "main.tsp");
+  const filePath = "/standalone/file.tsp";
 
   vi.mocked(host.stat).mockImplementation(async (path) => {
-    return path === expected ? ({ isFile: () => true } as any) : ({ isFile: () => false } as any);
-  });
-
-  vi.mocked(host.readFile).mockImplementation(async (path: string) => {
-    // Return empty package.json
-    return { text: "{}" } as any;
+    // The initial path should be treated as a file, but no other files exist
+    return path === filePath ? ({ isFile: () => true } as any) : ({ isFile: () => false } as any);
   });
+  vi.mocked(host.readFile).mockResolvedValue({ text: "{}" } as any);
 
   const { log } = createLogger();
   const result = await resolveEntrypointFile(host, undefined, filePath, undefined, log);
-  expect(result).toBe(expected);
+  expect(result).toBe(filePath);
 });
 
-it("uses the given path as main when nothing else is found", async () => {
+it("uses main.tsp as default entrypoint when entrypoints is null or undefined and no package.json tspMain found", async () => {
   const host = createMockHost();
-  const filePath = "/standalone/file.tsp";
+  const dir = "/project";
+  const filePath = joinPaths(dir, "src", "file.tsp");
+  const expectedMainTsp = joinPaths(dir, "main.tsp");
 
+  // Mock host.stat to return isFile: true only for the expected main.tsp path
   vi.mocked(host.stat).mockImplementation(async (path) => {
-    // The initial path should be treated as a file, but no other files exist
-    return path === filePath ? ({ isFile: () => true } as any) : ({ isFile: () => false } as any);
+    return path === expectedMainTsp
+      ? ({ isFile: () => true } as any)
+      : ({ isFile: () => false } as any);
+  });
+
+  // Mock host.readFile to return empty package.json (no tspMain)
+  vi.mocked(host.readFile).mockImplementation(async (path) => {
+    if (path.endsWith("package.json")) {
+      return { text: "{}" } as any; // Empty package.json, no tspMain
+    }
+    throw new Error("File not found");
   });
-  vi.mocked(host.readFile).mockResolvedValue({ text: "{}" } as any);
 
   const { log } = createLogger();
-  const result = await resolveEntrypointFile(host, undefined, filePath, undefined, log);
-  expect(result).toBe(filePath);
+  const resultForNull = await resolveEntrypointFile(
+    host,
+    null, // Explicitly pass null for entrypoints
+    filePath,
+    undefined,
+    log,
+  );
+
+  expect(resultForNull).toBe(expectedMainTsp);
+
+  const resultForUndefined = await resolveEntrypointFile(
+    host,
+    undefined, // Explicitly pass undefined for entrypoints
+    filePath,
+    undefined,
+    log,
+  );
+
+  expect(resultForUndefined).toBe(expectedMainTsp);
 });