[PATCH v6 proxmox-backup 09/18] datastore: test FixedIndexWriter

[Robert Obkircher <r.obkircher@proxmox.com>]

Write fixed and dynamically sized fidx files to a temporary directory.
Compare the resulting files directly (ignoring uuid and ctime bytes)
and also read them back using the reader.

The chunk hashes are just dummy values that don't actually exist in a
chunk store.

Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 pbs-datastore/src/fixed_index.rs | 178 +++++++++++++++++++++++++++++++
 1 file changed, 178 insertions(+)

diff --git a/pbs-datastore/src/fixed_index.rs b/pbs-datastore/src/fixed_index.rs
index 3807ba35..350bf2ed 100644
--- a/pbs-datastore/src/fixed_index.rs
+++ b/pbs-datastore/src/fixed_index.rs
@@ -567,3 +567,181 @@ impl FixedIndexWriter {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::fs;
+
+    use super::*;
+    use crate::temp_dir::TempDir;
+
+    const CS: u32 = 4096;
+
+    #[test]
+    fn test_empty() {
+        let dir = TempDir::new().unwrap();
+        let path = dir.path().join("test_empty");
+        let mut w = FixedIndexWriter::create(&path, None, CS).unwrap();
+
+        assert!(w.add_digest(0, &[1u8; 32]).is_err(), "out of bounds");
+
+        assert_eq!(0, w.size);
+        assert_eq!(0, w.index_length(), "returns length, not capacity");
+        assert_eq!(FixedIndexWriter::INITIAL_CAPACITY, w.index_capacity);
+
+        assert!(w.close().is_err(), "should refuse to create empty file");
+
+        drop(w);
+        assert!(!fs::exists(path).unwrap());
+
+        dir.delete().unwrap();
+    }
+
+    #[test]
+    fn test_single_partial_chunk() {
+        let dir = TempDir::new().unwrap();
+        let path = dir.path().join("test_single_partial_chunk");
+        let mut w = FixedIndexWriter::create(&path, None, CS).unwrap();
+
+        let size = CS as u64 - 1;
+        let expected = test_data(size);
+        w.grow_to_size(size).unwrap();
+        expected[0].add_to(&mut w);
+
+        w.close().unwrap();
+        drop(w);
+
+        check_with_reader(&path, size, &expected);
+        compare_to_known_size_writer(&path, size, &expected);
+
+        dir.delete().unwrap();
+    }
+
+    #[test]
+    fn test_grow_to_multiples_of_chunk_size() {
+        let dir = TempDir::new().unwrap();
+        let path = dir.path().join("test_grow_to_multiples_of_chunk_size");
+        let mut w = FixedIndexWriter::create(&path, None, CS).unwrap();
+
+        let initial = FixedIndexWriter::INITIAL_CAPACITY;
+        let steps = [1, 2, initial, initial + 1, 5 * initial, 10 * initial + 1];
+        let expected = test_data(*steps.last().unwrap() as u64 * CS as u64);
+
+        let mut begin = 0;
+        for chunk_count in steps {
+            let last = &expected[chunk_count - 1];
+            w.grow_to_size(last.end).unwrap();
+            assert_eq!(last.index + 1, w.index_length());
+            assert!(w.add_digest(last.index + 1, &[1u8; 32]).is_err());
+
+            for c in expected[begin..chunk_count].iter().rev() {
+                c.add_to(&mut w);
+            }
+            begin = chunk_count;
+        }
+        w.close().unwrap();
+        drop(w);
+
+        let size = expected.len() as u64 * CS as u64;
+        check_with_reader(&path, size, &expected);
+        compare_to_known_size_writer(&path, size, &expected);
+
+        dir.delete().unwrap();
+    }
+
+    #[test]
+    fn test_grow_to_misaligned_size() {
+        let dir = TempDir::new().unwrap();
+        let path = dir.path().join("test_grow_to_misaligned_size");
+        let mut w = FixedIndexWriter::create(&path, None, CS).unwrap();
+
+        let size = (FixedIndexWriter::INITIAL_CAPACITY as u64 + 42) * CS as u64 - 1; // last is not full
+        let expected = test_data(size);
+
+        w.grow_to_size(size).unwrap();
+        assert!(w.grow_to_size(size + 1).is_err(), "size must be fixed now");
+        assert_eq!(expected.len(), w.index_length());
+        assert!(w.add_digest(expected.len(), &[1u8; 32]).is_err());
+
+        for c in expected.iter().rev() {
+            c.add_to(&mut w);
+        }
+
+        w.close().unwrap();
+        drop(w);
+
+        check_with_reader(&path, size, &expected);
+        compare_to_known_size_writer(&path, size, &expected);
+
+        dir.delete().unwrap();
+    }
+
+    struct TestChunk {
+        digest: [u8; 32],
+        index: usize,
+        size: u32,
+        end: u64,
+    }
+
+    impl TestChunk {
+        fn add_to(&self, w: &mut FixedIndexWriter) {
+            assert_eq!(
+                self.index,
+                w.check_chunk_alignment(self.end, self.size as u64).unwrap()
+            );
+            w.add_digest(self.index, &self.digest).unwrap();
+        }
+    }
+
+    fn test_data(size: u64) -> Vec<TestChunk> {
+        (0..size.div_ceil(CS as u64))
+            .map(|index| {
+                let mut digest = [0u8; 32];
+                let i = &index.to_le_bytes();
+                for c in digest.chunks_mut(i.len()) {
+                    c.copy_from_slice(i);
+                }
+                let size = if ((index + 1) * CS as u64) <= size {
+                    CS
+                } else {
+                    (size % CS as u64) as u32
+                };
+                TestChunk {
+                    digest,
+                    index: index as usize,
+                    size,
+                    end: index * CS as u64 + size as u64,
+                }
+            })
+            .collect()
+    }
+
+    fn check_with_reader(path: &Path, size: u64, chunks: &[TestChunk]) {
+        let reader = FixedIndexReader::open(path).unwrap();
+        assert_eq!(size, reader.index_bytes());
+        assert_eq!(chunks.len(), reader.index_count());
+        for c in chunks {
+            assert_eq!(&c.digest, reader.index_digest(c.index).unwrap());
+        }
+    }
+
+    fn compare_to_known_size_writer(file: &Path, size: u64, chunks: &[TestChunk]) {
+        let mut path = file.to_path_buf();
+        path.set_extension("reference");
+        let mut w = FixedIndexWriter::create(&path, Some(size), CS).unwrap();
+        for c in chunks {
+            c.add_to(&mut w);
+        }
+        w.close().unwrap();
+        drop(w);
+
+        let mut reference = fs::read(file).unwrap();
+        let mut tested = fs::read(path).unwrap();
+
+        // ignore uuid and ctime
+        reference[8..32].fill(0);
+        tested[8..32].fill(0);
+
+        assert_eq!(reference, tested);
+    }
+}
-- 
2.47.3