It actually worked for win-server. So expanding tests.

Cargo.toml

@@ -21,6 +21,8 @@ serde_json = "1.0.73"
 
 [dev-dependencies]
 const_format = "0.2.23"
+# TODO update to 0.16 when it is released. 
+# It fixes https://github.com/la10736/rstest/issues/158, which is not showtopper, but minor annoyance.
 rstest = "0.15.0"
 once_cell = "1.16.0"
 

src/ffi.rs

@@ -139,6 +139,11 @@ pub fn set_file_compression<P: AsRef<Path>>(path: P, compress: bool) -> Result<(
     let handle = Handle::from_file(File::options().write(true).read(true).open(path)?);
 
     // mut, coz WinAPI rquires mut pointer
+    // documentation states that Windows supports only LZNT1, and it is also used by DEFAULT
+    // but practical tests show that on windows-server-22 DEFAULT doesn't compress a thing.
+    // Perhaps if we were doing compression manager or wothever -- more research would be required,
+    // but for tests hardcoding LZNT1 would suffice.
+    // We don't need be as future-proof for new algorithms in new windows releases.
     let mut compression_format: USHORT = if compress {
         COMPRESSION_FORMAT_LZNT1
     } else {

src/tests.rs

@@ -124,27 +124,28 @@ fn test_files_physical_size() {
     assert_size(concatcp!(TEST_PRE_CREATED_DIR, "text1.txt"), true, 4096);
     assert_size(concatcp!(TEST_PRE_CREATED_DIR, "text2.txt"), true, 12288);
 }
-#[test]
+
 #[cfg(windows)] // isn't supported on Unix (Theoretically possible on btrfs)
-fn test_compressed_files_physical_size() {
+#[rstest]
+#[case("b23_rand_c", 24)]
+#[case("b23_zero_c", 24)]
+#[case("b512_rand_c", 512)]
+#[case("b512_zero_c", 512)]
+#[case("b4000_rand_c", 8192)]
+#[case("b4000_zero_c", 0)]
+#[case("b4096_rand_c", 8192)]
+#[case("b4096_zero_c", 0)]
+#[case("b8000_rand_c", 12288)]
+#[case("b8192_rand_c", 12288)]
+#[case("b8192_zero_c", 0)]
+#[case("rand_1000_c", 4096)]
+#[case("text1_c.txt", 4096)]
+#[case("text2_c.txt", 4096)]
+fn test_compressed_files_physical_size(#[case] file: &str, #[case] size: u64) {
     PREPARE_COMPRESSION_SAMPLES.as_ref().unwrap();
+    let file = String::from(TEST_PRE_CREATED_DIR) + file;
 
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b23_rand_c"), true, 24);
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b23_zero_c"), true, 24);
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b512_rand_c"), true, 512);
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b512_zero_c"), true, 512);
-
-    // Unreproducible: my Win10 -- 8192; WinServer(github) -- 4096
-    //assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b4000_rand_c"), true, 8192);
-    //assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b4000_zero_c"), true, 0);
-    // CI assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b4096_rand_c"), true, 8192);
-    // CI assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b4096_zero_c"), true, 0);
-    // assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b8000_rand_c"), true, 12288);
-    // assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b8192_rand_c"), true, 12288);
-    // CI assert_size(concatcp!(TEST_PRE_CREATED_DIR, "b8192_zero_c"), true, 0);
-    // assert_size(concatcp!(TEST_PRE_CREATED_DIR, "rand_1000_c"), true, 4096);
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "text1_c.txt"), true, 4096);
-    assert_size(concatcp!(TEST_PRE_CREATED_DIR, "text2_c.txt"), true, 4096);
+    assert_size(&file, true, size);
 }
 
 #[allow(non_snake_case)]