[DebuggerV2] Enable debug_v2_ops_test & debug_events_writer_test on Windows

- A test in debug_v2_ops_test previously called `np.power(2, 53)` without specifying
  dtype. As a result, the output had the int32 dtype on Windows and caused
  overflowing. This apparently does not happen on Linux or Mac.
  - This CL fixes that by explicitly specifying `dtype=np.int64` in the call.
- In debug_events_write.cc, check for whether the DebugEventsWriter instance
  is initialized and return early if not so.
  - This resolves a directory-not-empty test failure in debug_events_writer_test
    on Windows

This is a step towards fixing #43608

PiperOrigin-RevId: 349569528
Change-Id: I8112f8faebe662542e80c03d5d95e8e089446fe8

tensorflow/core/util/BUILD

@@ -783,7 +783,6 @@ tf_cc_test(
         "//conditions:default": [],
     }),
     linkstatic = tf_kernel_tests_linkstatic(),
-    tags = ["no_windows"],  # b/150411480
     deps = [
         "//tensorflow/core:framework",
         "//tensorflow/core:lib",

tensorflow/core/util/debug_events_writer.cc

@@ -403,6 +403,13 @@ string DebugEventsWriter::FileName(DebugEventFileType type) {
 }
 
 Status DebugEventsWriter::Close() {
+  {
+    mutex_lock l(initialization_mu_);
+    if (!is_initialized_) {
+      return Status::OK();
+    }
+  }
+
   std::vector<string> failed_to_close_files;
 
   if (metadata_writer_ != nullptr) {

tensorflow/python/debug/BUILD

@@ -776,9 +776,6 @@ cuda_py_test(
     size = "medium",
     srcs = ["lib/debug_v2_ops_test.py"],
     python_version = "PY3",
-    tags = [
-        "no_windows",  # b/142475891
-    ],
     deps = [
         ":debug_events_reader",
         ":debug_events_writer",

tensorflow/python/debug/lib/debug_v2_ops_test.py

@@ -339,7 +339,7 @@ class DebugNumericSummaryV2Test(test_util.TensorFlowTestCase):
         debug_event_pb2.TensorDebugMode.SHAPE,
     ]
     # Maximum allowed tensor_id
-    tensor_id = np.power(2, 53)
+    tensor_id = np.power(2, 53, dtype=np.int64)
     for mode in modes:
       self.evaluate(
           gen_debug_ops.debug_numeric_summary_v2(