Raise error if mixing tsconfig.json and directives.

src/harness/fourslash.ts

@@ -2476,6 +2476,17 @@ module FourSlash {
             }
         }
 
+        // @Filename is the only directive that can be used in a test that contains tsconfig.json file.
+        if (containTSConfigJson(files)) {
+            let directive = getNonFileNameOptionInFileList(files);
+            if (directive == null) {
+                directive = getNonFileNameOptionInObject(globalOptions);
+            }
+            if (directive !== null) {
+                throw Error("It is not allowed to use tsconfig.json along with directive '" + directive + "'");
+            }
+        }
+
         return {
             markerPositions,
             markers,
@@ -2485,6 +2496,34 @@ module FourSlash {
         };
     }
 
+    function containTSConfigJson(files: FourSlashFile[]): boolean {
+        for (let i = 0; i < files.length; ++i) {
+            if (files[i].fileOptions['Filename'] === 'tsconfig.json') {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    function getNonFileNameOptionInFileList(files: FourSlashFile[]): string {
+        for (let i = 0; i < files.length; ++i) {
+            let option = getNonFileNameOptionInObject(files[i].fileOptions);
+            if (option !== null) {
+                return option;
+            }
+        }
+        return null;
+    }
+
+    function getNonFileNameOptionInObject(optionObject: { [s: string]: string }): string {
+        for (let option in optionObject) {
+            if (option !== metadataOptionNames.fileName) {
+                return option;
+            }
+        }
+        return null;
+    }
+
     const enum State {
         none,
         inSlashStarMarker,