Cleanup test_fs_write. NFC (#24701)

- Rename test (test_write.cpp is very generic and test_fs_write matches
the name of the test)
- Convert to C
- Format code

Author: sbc100

test/fs/test_fs_write.c

@@ -0,0 +1,46 @@
+// Copyright 2016 The Emscripten Authors.  All rights reserved.
+// Emscripten is available under two separate licenses, the MIT license and the
+// University of Illinois/NCSA Open Source License.  Both these licenses can be
+// found in the LICENSE file.
+
+// https://github.com/emscripten-core/emscripten/pull/4705: Test that FS.write() with canOwn=true works.
+
+#include <stdio.h>
+
+#include <emscripten/emscripten.h>
+
+int main() {
+  EM_ASM(
+    var stream = FS.open('testfile', 'w+');
+
+    var data = new Uint8Array(128);
+    var str = "Hello! ";
+    stringToUTF8Array(str, data, 0, lengthBytesUTF8(str)+1);
+    data = data.subarray(0, lengthBytesUTF8(str));
+    FS.write(stream, data, 0, lengthBytesUTF8(str), 0, /*canOwn=*/true);
+    var pos = lengthBytesUTF8(str);
+
+    str = '1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890';
+    data = new Uint8Array(str.length+1);
+    stringToUTF8Array(str, data, 0, lengthBytesUTF8(str)+1);
+    FS.write(stream, data, 0, lengthBytesUTF8(str)+1, pos, /*canOwn=*/false);
+
+    FS.close(stream);
+
+    var ex;
+    try {
+      FS.write(stream, data, 0, lengthBytesUTF8(str)+1, pos, /*canOwn=*/false);
+    } catch (err) {
+      ex = err;
+    }
+    assert(ex.name === 'ErrnoError' && ex.errno === 8 /* EBADF */)
+  );
+
+  FILE* file = fopen("testfile", "r");
+  char* line = NULL;
+  size_t n;
+  getline(&line, &n, file);
+  printf("read %s\n", line);
+
+  return 0;
+}

test/fs/test_write.out renamed to test/fs/test_fs_write.out

@@ -1 +1 @@
-read Hello! 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+read Hello! 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890

test/fs/test_write.cpp

@@ -5905,7 +5905,7 @@ def test_fs_js_api(self):
   def test_fs_write(self):
     if self.get_setting('WASMFS'):
       self.set_setting("FORCE_FILESYSTEM")
-    self.do_run_in_out_file_test('fs/test_write.cpp')
+    self.do_run_in_out_file_test('fs/test_fs_write.c')
 
   @also_with_noderawfs
   def test_fs_emptyPath(self):