Add custom baseline format for smart selection

src/harness/fourslash.ts

@@ -1417,12 +1417,7 @@ Actual: ${stringify(fullActual)}`);
         }
 
         public baselineCurrentFileBreakpointLocations() {
-            let baselineFile = this.testData.globalOptions[MetadataOptionNames.baselineFile];
-            if (!baselineFile) {
-                baselineFile = this.activeFile.fileName.replace(this.basePath + "/breakpointValidation", "bpSpan");
-                baselineFile = baselineFile.replace(ts.Extension.Ts, ".baseline");
-
-            }
+            const baselineFile = this.getBaselineFileName().replace(this.basePath + "/breakpointValidation", "bpSpan");
             Harness.Baseline.runBaseline(baselineFile, this.baselineCurrentFileLocations(pos => this.getBreakpointStatementLocation(pos)!));
         }
 
@@ -1497,8 +1492,7 @@ Actual: ${stringify(fullActual)}`);
         }
 
         public baselineQuickInfo() {
-            const baselineFile = this.testData.globalOptions[MetadataOptionNames.baselineFile] ||
-                ts.getBaseFileName(this.activeFile.fileName).replace(ts.Extension.Ts, ".baseline");
+            const baselineFile = this.getBaselineFileName();
             Harness.Baseline.runBaseline(
                 baselineFile,
                 stringify(
@@ -1508,6 +1502,39 @@ Actual: ${stringify(fullActual)}`);
                     }))));
         }
 
+        public baselineSmartSelection() {
+            const n = ts.sys.newLine;
+            const baselineFile = this.getBaselineFileName();
+            const markers = this.getMarkers();
+            const fileContent = this.activeFile.content;
+            const text = markers.map(marker => {
+                const baselineContent = [fileContent.slice(0, marker.position) + "/**/" + fileContent.slice(marker.position) + n];
+                let selectionRange: ts.SelectionRange | undefined = this.languageService.getSmartSelectionRange(this.activeFile.fileName, marker.position);
+                while (selectionRange) {
+                    const { textSpan } = selectionRange;
+                    let masked = Array.from(fileContent).map((char, index) => {
+                        const charCode = char.charCodeAt(0);
+                        if (index >= textSpan.start && index < ts.textSpanEnd(textSpan)) {
+                            return char === " " ? "•" : ts.isLineBreak(charCode) ? `↲${n}` : char;
+                        }
+                        return ts.isLineBreak(charCode) ? char : " ";
+                    }).join("");
+                    masked = masked.replace(/^\s*$\r?\n?/gm, ""); // Remove blank lines
+                    const isRealCharacter = (char: string) => char !== "•" && char !== "↲" && !ts.isWhiteSpaceLike(char.charCodeAt(0));
+                    const leadingWidth = Array.from(masked).findIndex(isRealCharacter);
+                    const trailingWidth = ts.findLastIndex(Array.from(masked), isRealCharacter);
+                    masked = masked.slice(0, leadingWidth)
+                        + masked.slice(leadingWidth, trailingWidth).replace(/•/g, " ").replace(/↲/g, "")
+                        + masked.slice(trailingWidth);
+                    baselineContent.push(masked);
+                    selectionRange = selectionRange.parent;
+                }
+                return baselineContent.join(n);
+            }).join(n.repeat(2) + "=".repeat(80) + n.repeat(2));
+
+            Harness.Baseline.runBaseline(baselineFile, text);
+        }
+
         public printBreakpointLocation(pos: number) {
             Harness.IO.log("\n**Pos: " + pos + " " + this.spanInfoToString(this.getBreakpointStatementLocation(pos)!, "  "));
         }
@@ -1562,6 +1589,11 @@ Actual: ${stringify(fullActual)}`);
             Harness.IO.log(stringify(help.items[help.selectedItemIndex]));
         }
 
+        private getBaselineFileName() {
+            return this.testData.globalOptions[MetadataOptionNames.baselineFile] ||
+                ts.getBaseFileName(this.activeFile.fileName).replace(ts.Extension.Ts, ".baseline");
+        }
+
         private getSignatureHelp({ triggerReason }: FourSlashInterface.VerifySignatureHelpOptions): ts.SignatureHelpItems | undefined {
             return this.languageService.getSignatureHelpItems(this.activeFile.fileName, this.currentCaretPosition, {
                 triggerReason
@@ -3973,6 +4005,10 @@ namespace FourSlashInterface {
             this.state.baselineQuickInfo();
         }
 
+        public baselineSmartSelection() {
+            this.state.baselineSmartSelection();
+        }
+
         public nameOrDottedNameSpanTextIs(text: string) {
             this.state.verifyCurrentNameOrDottedNameSpanText(text);
         }

tests/cases/fourslash/fourslash.ts

@@ -244,6 +244,7 @@ declare namespace FourSlashInterface {
         baselineGetEmitOutput(insertResultsIntoVfs?: boolean): void;
         getEmitOutput(expectedOutputFiles: ReadonlyArray<string>): void;
         baselineQuickInfo(): void;
+        baselineSmartSelection(): void;
         nameOrDottedNameSpanTextIs(text: string): void;
         outliningSpansInCurrentFile(spans: Range[]): void;
         todoCommentsInCurrentFile(descriptors: string[]): void;
@@ -508,7 +509,7 @@ declare namespace FourSlashInterface {
         readonly importModuleSpecifierEnding?: "minimal" | "index" | "js";
     }
     interface CompletionsOptions {
-        readonly marker?: ArrayOrSingle<string | Marker>,
+        readonly marker?: ArrayOrSingle<string | Marker>;
         readonly isNewIdentifierLocation?: boolean;
         readonly isGlobalCompletion?: boolean;
         readonly exact?: ArrayOrSingle<ExpectedCompletionEntry>;