fourslash: Add 'goToMarkerOrRange' helper (#28057)

Author: Andy

src/harness/fourslash.ts

@@ -1181,12 +1181,7 @@ namespace FourSlash {
             }));
 
             for (const start of toArray<string | Range>(starts)) {
-                if (typeof start === "string") {
-                    this.goToMarker(start);
-                }
-                else {
-                    this.goToRangeStart(start);
-                }
+                this.goToMarkerOrRange(start);
                 const fullActual = ts.map<ts.ReferencedSymbol, ReferenceGroupJson>(this.findReferencesAtCaret(), ({ definition, references }, i) => {
                     const text = definition.displayParts.map(d => d.text).join("");
                     return {
@@ -1203,15 +1198,7 @@ namespace FourSlash {
         }
 
         public verifyNoReferences(markerNameOrRange?: string | Range) {
-            if (markerNameOrRange) {
-                if (ts.isString(markerNameOrRange)) {
-                    this.goToMarker(markerNameOrRange);
-                }
-                else {
-                    this.goToRangeStart(markerNameOrRange);
-                }
-            }
-
+            if (markerNameOrRange) this.goToMarkerOrRange(markerNameOrRange);
             const refs = this.getReferencesAtCaret();
             if (refs && refs.length) {
                 this.raiseError(`Expected getReferences to fail, but saw references: ${stringify(refs)}`);
@@ -2053,6 +2040,14 @@ Actual: ${stringify(fullActual)}`);
             this.goToPosition(len);
         }
 
+        private goToMarkerOrRange(markerOrRange: string | Range) {
+            if (typeof markerOrRange === "string") {
+                this.goToMarker(markerOrRange);
+            } else {
+                this.goToRangeStart(markerOrRange);
+            }
+        }
+
         public goToRangeStart({ fileName, pos }: Range) {
             this.openFile(fileName);
             this.goToPosition(pos);