Merge branch 'feat/p2-writer-groups-links' into feat/p2-perf-coverage

# Conflicts:
#	CHANGELOG.md
#	crates/clawhdf5-tools/tests/h5rs_interop.rs

crates/clawhdf5-format/tests/writer_meta_tests.rs

@@ -528,33 +528,50 @@ fn h5py_reads_all_attributes_next_to_an_empty_string() {
 // ---- 6. path-like names ----
 
 #[test]
-fn slash_in_a_group_or_dataset_name_is_an_error() {
-    // Measured: create_group("a/b") wrote one link literally named "a/b",
-    // which h5py cannot reach ("component not found"). The writer has no
-    // nested groups, so such names are refused.
+fn path_names_create_nested_groups() {
+    // create_group("a/b") used to write one link literally named "a/b",
+    // which h5py cannot reach ("component not found"); then such names were
+    // refused. Now a path creates its missing intermediate groups, as h5py
+    // does.
     let mut fw = FileWriter::new();
     let mut g = fw.create_group("a/b");
     g.create_dataset("c").with_f64_data(&[1.0]);
     fw.add_group(g.finish());
-    assert!(fw.finish().is_err());
-
-    let mut fw = FileWriter::new();
-    fw.create_dataset("x/y").with_f64_data(&[1.0]);
-    assert!(fw.finish().is_err());
-
-    let mut fw = FileWriter::new();
+    fw.create_dataset("x/y").with_f64_data(&[2.0]);
+    fw.create_dataset("/a/b/z").with_f64_data(&[3.0]);
     let mut g = fw.create_group("g");
-    g.create_dataset("x/y").with_f64_data(&[1.0]);
+    g.create_dataset("x/y").with_f64_data(&[4.0]);
     fw.add_group(g.finish());
-    assert!(fw.finish().is_err());
+    let bytes = fw.finish().unwrap();
+    for path in ["a", "a/b", "a/b/c", "a/b/z", "x", "x/y", "g/x", "g/x/y"] {
+        header_at(&bytes, path);
+    }
+}
 
-    for bad in ["", "."] {
+#[test]
+fn names_that_are_not_valid_link_names_are_errors() {
+    for bad in ["", ".", "a//b", "a/", "a/./b", "/"] {
         let mut fw = FileWriter::new();
         fw.create_dataset(bad).with_f64_data(&[1.0]);
         assert!(fw.finish().is_err(), "{bad:?}");
     }
+    // An absolute path inside a group, and a name used twice.
+    let mut fw = FileWriter::new();
+    let mut g = fw.create_group("g");
+    g.create_dataset("/x").with_f64_data(&[1.0]);
+    fw.add_group(g.finish());
+    assert!(fw.finish().is_err());
+    let mut fw = FileWriter::new();
+    fw.create_dataset("x").with_f64_data(&[1.0]);
+    fw.create_dataset("x").with_f64_data(&[1.0]);
+    assert!(fw.finish().is_err());
+    // A dataset in the way of a path.
+    let mut fw = FileWriter::new();
+    fw.create_dataset("x").with_f64_data(&[1.0]);
+    fw.create_dataset("x/y").with_f64_data(&[1.0]);
+    assert!(fw.finish().is_err());
 
-    // One level of groups still works, and '/' stays legal in attribute names.
+    // '/' stays legal in attribute names.
     let mut fw = FileWriter::new();
     let mut g = fw.create_group("g");
     g.create_dataset("c").with_f64_data(&[1.0]);