Handle empty string when getting file version (#51689)

* Test for empty string change

* Fix empty string for file versioning

src/compiler/tsbuildPublic.ts

@@ -1811,7 +1811,7 @@ function getUpToDateStatusWorker(state: SolutionBuilderState, project: ParsedCom
                 if (!buildInfoVersionMap) buildInfoVersionMap = getBuildInfoFileVersionMap(buildInfoProgram, buildInfoPath!, host);
                 version = buildInfoVersionMap.get(toPath(state, inputFile));
                 const text = version ? state.readFileWithCache(inputFile) : undefined;
-                currentVersion = text && getSourceFileVersionAsHashFromText(host, text);
+                currentVersion = text !== undefined ? getSourceFileVersionAsHashFromText(host, text) : undefined;
                 if (version && version === currentVersion) pseudoInputUpToDate = true;
             }
 

src/compiler/watchPublic.ts

@@ -715,7 +715,7 @@ export function createWatchProgram<T extends BuilderProgram>(host: WatchCompiler
         if (hostSourceFile.version) return hostSourceFile.version;
         // Read file and get new version
         const text = readFileWithCache(path);
-        return text ? getSourceFileVersionAsHashFromText(compilerHost, text) : undefined;
+        return text !== undefined ? getSourceFileVersionAsHashFromText(compilerHost, text) : undefined;
     }
 
     function onReleaseOldSourceFile(oldSourceFile: SourceFile, _oldOptions: CompilerOptions, hasSourceFileByPath: boolean) {

src/testRunner/unittests/tscWatch/watchEnvironment.ts

@@ -717,6 +717,16 @@ describe("unittests:: tsc-watch:: watchEnvironment:: tsc-watch with different po
                 change: sys => sys.replaceFileText("/user/username/projects/project/main.ts", "Hello", "Hello World"),
                 timeouts: sys => sys.runQueuedTimeoutCallbacks(),
             },
+            {
+                caption: "receive another change event without modifying the file",
+                change: sys => sys.invokeFsWatches("/user/username/projects/project/main.ts", "change", /*modifiedTime*/ undefined, /*useTildeSuffix*/ undefined),
+                timeouts: sys => sys.runQueuedTimeoutCallbacks(),
+            },
+            {
+                caption: "change main.ts to empty text",
+                change: sys => sys.writeFile("/user/username/projects/project/main.ts", ""),
+                timeouts: sys => sys.runQueuedTimeoutCallbacks(),
+            },
             {
                 caption: "receive another change event without modifying the file",
                 change: sys => sys.invokeFsWatches("/user/username/projects/project/main.ts", "change", /*modifiedTime*/ undefined, /*useTildeSuffix*/ undefined),

tests/baselines/reference/tsbuildWatch/noEmit/does-not-go-in-loop-when-watching-when-no-files-are-emitted-with-incremental.js

@@ -136,25 +136,11 @@ Output::
 >> Screen clear
 [12:00:36 AM] File change detected. Starting incremental compilation...
 
-[[90m12:00:37 AM[0m] Project 'tsconfig.json' is out of date because output 'tsconfig.tsbuildinfo' is older than input 'a.js'
+[[90m12:00:37 AM[0m] Project 'tsconfig.json' is up to date but needs to update timestamps of output files that are older than input files
 
-[[90m12:00:38 AM[0m] Building project '/user/username/projects/myproject/tsconfig.json'...
+[[90m12:00:38 AM[0m] Found 0 errors. Watching for file changes.
 
-[12:00:39 AM] Found 0 errors. Watching for file changes.
-
-
-
-Program root files: ["/user/username/projects/myproject/a.js","/user/username/projects/myproject/b.ts"]
-Program options: {"allowJs":true,"noEmit":true,"watch":true,"incremental":true,"configFilePath":"/user/username/projects/myproject/tsconfig.json"}
-Program structureReused: Not
-Program files::
-/a/lib/lib.d.ts
-/user/username/projects/myproject/a.js
-/user/username/projects/myproject/b.ts
-
-Semantic diagnostics in builder refreshed for::
 
-No shapes updated in the builder::
 
 PolledWatches::
 
@@ -182,13 +168,13 @@ const x = 10;
 
 Output::
 >> Screen clear
-[[90m12:00:43 AM[0m] File change detected. Starting incremental compilation...
+[[90m12:00:42 AM[0m] File change detected. Starting incremental compilation...
 
-[[90m12:00:44 AM[0m] Project 'tsconfig.json' is out of date because output 'tsconfig.tsbuildinfo' is older than input 'a.js'
+[[90m12:00:43 AM[0m] Project 'tsconfig.json' is out of date because output 'tsconfig.tsbuildinfo' is older than input 'a.js'
 
-[[90m12:00:45 AM[0m] Building project '/user/username/projects/myproject/tsconfig.json'...
+[[90m12:00:44 AM[0m] Building project '/user/username/projects/myproject/tsconfig.json'...
 
-[[90m12:00:53 AM[0m] Found 0 errors. Watching for file changes.
+[[90m12:00:52 AM[0m] Found 0 errors. Watching for file changes.
 
 
 

tests/baselines/reference/tscWatch/watchEnvironment/fsEvent-for-change-is-repeated.js

@@ -121,6 +121,84 @@ var a = "Hello World";
 
 
 
+Change:: receive another change event without modifying the file
+
+Input::
+
+Output::
+FileWatcher:: Triggered with main.ts 1:: WatchInfo: main.ts 250 undefined Source file
+Scheduling update
+Elapsed:: *ms FileWatcher:: Triggered with main.ts 1:: WatchInfo: main.ts 250 undefined Source file
+Synchronizing program
+
+
+PolledWatches::
+/user/username/projects/project/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/user/username/projects/project/main.ts:
+  {}
+/a/lib/lib.d.ts:
+  {}
+
+FsWatchesRecursive::
+
+exitCode:: ExitStatus.undefined
+
+
+Change:: change main.ts to empty text
+
+Input::
+//// [/user/username/projects/project/main.ts]
+
+
+
+Output::
+FileWatcher:: Triggered with main.ts 1:: WatchInfo: main.ts 250 undefined Source file
+Scheduling update
+Elapsed:: *ms FileWatcher:: Triggered with main.ts 1:: WatchInfo: main.ts 250 undefined Source file
+Synchronizing program
+[12:00:34 AM] File change detected. Starting incremental compilation...
+
+CreatingProgramWith::
+  roots: ["main.ts"]
+  options: {"watch":true,"extendedDiagnostics":true}
+[12:00:38 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["main.ts"]
+Program options: {"watch":true,"extendedDiagnostics":true}
+Program structureReused: Completely
+Program files::
+/a/lib/lib.d.ts
+main.ts
+
+Semantic diagnostics in builder refreshed for::
+main.ts
+
+Shape signatures in builder refreshed for::
+/user/username/projects/project/main.ts (used version)
+
+PolledWatches::
+/user/username/projects/project/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/user/username/projects/project/main.ts:
+  {}
+/a/lib/lib.d.ts:
+  {}
+
+FsWatchesRecursive::
+
+exitCode:: ExitStatus.undefined
+
+//// [/user/username/projects/project/main.js]
+
+
+
 Change:: receive another change event without modifying the file
 
 Input::