fix(51170): Completing an unimplemented property overwrites rest of line (#51175)

* fix(51170): skip insertText for class members with existing initializer

* skip insertText for class members with existing tokens

Author: a-tarasyuk

src/services/completions.ts

@@ -764,7 +764,7 @@ namespace ts.Completions {
         if (preferences.includeCompletionsWithClassMemberSnippets &&
             preferences.includeCompletionsWithInsertText &&
             completionKind === CompletionKind.MemberLike &&
-            isClassLikeMemberCompletion(symbol, location)) {
+            isClassLikeMemberCompletion(symbol, location, sourceFile)) {
             let importAdder;
             ({ insertText, isSnippet, importAdder, replacementSpan } = getEntryForMemberCompletion(host, program, options, preferences, name, symbol, location, contextToken, formatContext));
             sortText = SortText.ClassMemberSnippets; // sortText has to be lower priority than the sortText for keywords. See #47852.
@@ -846,7 +846,7 @@ namespace ts.Completions {
         };
     }
 
-    function isClassLikeMemberCompletion(symbol: Symbol, location: Node): boolean {
+    function isClassLikeMemberCompletion(symbol: Symbol, location: Node, sourceFile: SourceFile): boolean {
         // TODO: support JS files.
         if (isInJSFile(location)) {
             return false;
@@ -884,6 +884,7 @@ namespace ts.Completions {
                     location.parent.parent &&
                     isClassElement(location.parent) &&
                     location === location.parent.name &&
+                    location.parent.getLastToken(sourceFile) === location.parent.name &&
                     isClassLike(location.parent.parent)
                 ) ||
                 (

tests/cases/fourslash/completionsOverridingProperties.ts renamed to tests/cases/fourslash/completionsOverridingProperties1.ts

@@ -0,0 +1,21 @@
+/// <reference path="fourslash.ts" />
+
+////interface I {
+////    prop: string;
+////}
+////class C implements I {
+////    public pr/**/: string = 'foo';
+////}
+
+verify.completions({
+    marker: "",
+    includes: [
+        { name: "prop", isSnippet: undefined, insertText: undefined }
+    ],
+    isNewIdentifierLocation: true,
+    preferences: {
+        includeCompletionsWithInsertText: true,
+        includeCompletionsWithSnippetText: true,
+        includeCompletionsWithClassMemberSnippets: true,
+    }
+});

tests/cases/fourslash/completionsOverridingProperties2.ts

@@ -0,0 +1,21 @@
+/// <reference path="fourslash.ts" />
+
+////interface I {
+////    prop: string;
+////}
+////class C implements I {
+////    public pr/**/: string | number;
+////}
+
+verify.completions({
+    marker: "",
+    includes: [
+        { name: "prop", isSnippet: undefined, insertText: undefined }
+    ],
+    isNewIdentifierLocation: true,
+    preferences: {
+        includeCompletionsWithInsertText: true,
+        includeCompletionsWithSnippetText: true,
+        includeCompletionsWithClassMemberSnippets: true,
+    }
+});