Dev: Have a clickable link for a new baseline created (microsoft#44552)

* Have a clickable link for a new baseline created

* Use joinPath instead:

Author: Orta Therox

src/harness/harnessIO.ts

@@ -25,6 +25,7 @@ namespace Harness {
         tryEnableSourceMapsForHost?(): void;
         getEnvironmentVariable?(name: string): string;
         getMemoryUsage?(): number | undefined;
+        joinPath(...components: string[]): string
     }
 
     export let IO: IO;
@@ -62,6 +63,10 @@ namespace Harness {
             return dirPath === path ? undefined : dirPath;
         }
 
+        function joinPath(...components: string[]) {
+            return pathModule.join(...components);
+        }
+
         function enumerateTestFiles(runner: RunnerBase) {
             return runner.getTestFiles();
         }
@@ -156,6 +161,7 @@ namespace Harness {
             tryEnableSourceMapsForHost: () => ts.sys.tryEnableSourceMapsForHost && ts.sys.tryEnableSourceMapsForHost(),
             getMemoryUsage: () => ts.sys.getMemoryUsage && ts.sys.getMemoryUsage(),
             getEnvironmentVariable: name => ts.sys.getEnvironmentVariable(name),
+            joinPath
         };
     }
 
@@ -1388,7 +1394,12 @@ namespace Harness {
                     throw new Error(`The baseline file ${relativeFileName} has changed.${ts.ForegroundColorEscapeSequences.Grey}\n\n${patch}`);
                 }
                 else {
-                    throw new Error(`The baseline file ${relativeFileName} has changed.`);
+                    if (!IO.fileExists(expected)) {
+                        throw new Error(`New baseline created at ${IO.joinPath("tests", "baselines","local", relativeFileName)}`);
+                    }
+                    else {
+                        throw new Error(`The baseline file ${relativeFileName} has changed.`);
+                    }
                 }
             }
         }