feat(diff): show diff statistics

[nardoor]

closes #440

Description

The proposed code contains:

• a DiffStatistics structure used to hold count of stats
  • this structure offers a few helping functions that will look at a given NodeType to increment the associated counter
  • it has a Display implementation used to display the statistics in STDOUT
• this structure is used in the diff function

Exemple

rustic --log-level debug -r test-repo --password password diff 8e57051d:config ./config
[INFO] using no config file, none of these exist: /home/nardor/.config/rustic/rustic.toml, /etc/rustic/rustic.toml, ./rustic.toml
[INFO] repository local:test-repo: password is correct.
[INFO] using cache at /home/nardor/.cache/rustic/3797e1fe324e97ac068e303e672da3d34af09cd73888bcfd09538cd72692bf7d
[00:00:00] reading index...               ████████████████████████████████████████          2/2                               
[00:00:00] getting snapshot...            ████████████████████████████████████████          0                                
[INFO] getting snapshot...
[00:00:00] getting snapshot...            ████████████████████████████████████████          0                                 
-    "README.md"
M    "bar"
+    "new_dir"
+    "new_dir/new_file"
-    "services"
-    "services/b2.toml"
-    "services/rclone_ovh-hot-cold.toml"
-    "services/s3_aws.toml"
-    "services/s3_idrive.toml"
-    "services/sftp.toml"
-    "services/sftp_hetzner_sbox.toml"
-    "services/webdav_owncloud_nextcloud.toml"
Files:	1 new,	8 removed, 	1 changed
Dirs:	1 new,	1 removed
Others:	0 new,	0 removed

Testing

I am not sure what tests I can add.
Please let me know if you think of any test about this.

Thanks in advance for any feedback.

[aawsome]

Thanks for the PR! I would only request small changes:

• maybe name "file changed" into "content changed"
• and either add more detailed "change types" for the other changes which are currently collected under "file changed"
• or add a single "other changes" to collect all those other changes.

[aawsome]

@nardoor Sorry for the late review. About tests, in rustic we only have integration tests (and very few) so you could try to generate some testdata in a tar-files (or just one tar and modify files by hand), run the command and check the output (maybe using the insta crate). But this is pretty complicated as these tests may be OS-specific. In rustic we are not that strict requesting unit tests, so far.

[nardoor]

Hello @aawsome,

Thanks for taking the time to review the proposed changes.
I'll gladly apply the review comments asap.

About tests, I might try to add an integration test about this feature, but if I get stuck on some OS specifics as you warned me, I might leave it (for later?).

[nardoor]

with new types added:

❯ ./target/debug/rustic --log-level debug -r test-repo --password password diff 8e57051d:config ./config  --metadata
[INFO] using no config file, none of these exist: /home/nardor/.config/rustic/rustic.toml, /etc/rustic/rustic.toml, ./rustic.toml
[INFO] repository local:test-repo: password is correct.
[INFO] using cache at /home/nardor/.cache/rustic/3797e1fe324e97ac068e303e672da3d34af09cd73888bcfd09538cd72692bf7d
[00:00:00] reading index...               ████████████████████████████████████████          7/7                                                                                              [00:00:00] getting snapshot...            ████████████████████████████████████████          0                                                                                                [INFO] getting snapshot...
U    "README.md"
-    "bar"
T    "full.toml"
+    "full.toml/coco"
+    "lnsymlink"
U    "local.toml"
+    "new_dir"
-    "services/b2.toml"
-    "services/rclone_ovh-hot-cold.toml"
-    "services/s3_aws.toml"
-    "services/s3_idrive.toml"
-    "services/sftp.toml"
-    "services/sftp_hetzner_sbox.toml"
-    "services/webdav_owncloud_nextcloud.toml"
Files   :	1 new,	8 removed,	0 changed
Symlinks:	1 new,	0 removed,	0 changed
Dirs    :	1 new,	0 removed
NodeType:	1 changed
Metadata:	2 changed

[aawsome]

LGTM! Thanks again @nardoor

I removed the unused "use" statement.

[nardoor]

Thanks for finishing the work and looking at my PR!