Add test for reporting errors from deep import.

Test case for #24986

Author: sheetalkamat

src/testRunner/unittests/tscWatchMode.ts

@@ -1270,6 +1270,46 @@ export default test;`;
                 checkOutputErrorsIncremental(host, expectedErrors);
             }
         });
+
+        it("updates errors when deep import file changes", () => {
+            const currentDirectory = "/user/username/projects/myproject";
+            const aFile: File = {
+                path: `${currentDirectory}/a.ts`,
+                content: `import {B} from './b';
+declare var console: any;
+let b = new B();
+console.log(b.c.d);`
+            };
+            const bFile: File = {
+                path: `${currentDirectory}/b.ts`,
+                content: `import {C} from './c';
+export class B
+{
+    c = new C();
+}`
+            };
+            const cFile: File = {
+                path: `${currentDirectory}/c.ts`,
+                content: `export class C
+{
+    d = 1;
+}`
+            };
+            const config: File = {
+                path: `${currentDirectory}/tsconfig.json`,
+                content: `{}`
+            };
+            const files = [aFile, bFile, cFile, config, libFile];
+            const host = createWatchedSystem(files, { currentDirectory });
+            const watch = createWatchOfConfigFile("tsconfig.json", host);
+            checkProgramActualFiles(watch(), [aFile.path, bFile.path, cFile.path, libFile.path]);
+            checkOutputErrorsInitial(host, emptyArray);
+            host.writeFile(cFile.path, cFile.content.replace("d", "d2"));
+            host.runQueuedTimeoutCallbacks();
+            checkOutputErrorsIncremental(host, [
+                getDiagnosticOfFileFromProgram(watch(), aFile.path, aFile.content.lastIndexOf("d"), 1, Diagnostics.Property_0_does_not_exist_on_type_1, "d", "C")
+            ]);
+        });
     });
 
     describe("tsc-watch emit with outFile or out setting", () => {