feat: Add serialization traits to Status

[bitdivine]

Description

We would like to express the Status response printed by dfx as IDL and/or JSON. This requires corresponding serialization traits to be implemented for Status.

Contributes towards fixing: https://dfinity.atlassian.net/browse/SDK-1319

How Has This Been Tested?

Unit tests are included for serialization to JSON and IDL.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.
  • Not sure what is needed here, if anything. The traits should show up in the generated rustdoc and that is the documentation I look at most frequently when I wish to know how to serialize a type. On that basis I believe this is done.

[bitdivine]

Note: The cla test is hanging. Is this a known issue?

[bitdivine]

Note: I am not super happy about enabling a feature in code that may be used as a library. IDLValue is needed for tests only, but AFAIK there is no way of enabling a feature for tests only. Maybe the test is overkill. What do you think?

[smallstepman]

@bitdivine maybe you're looking for [dev-dependencies], would that work?
https://doc.rust-lang.org/rust-by-example/testing/dev_dependencies.html
https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#development-dependencies

[bitdivine]

AFAIK a different version of a crate can be added to dev-dependencies under an alias, but not the same version of the same crate with a different feature set. But I can try it just to be sure.

[smallstepman]

I see. Let me know, I'm curious

[bitdivine]

Yes: Experiment:

• I dropped the "values" feature from the candid dependency.
• I added a the candid crate under an alias in the dev dependencies.
• cargo check complained about the duplicate:

max@sinkpad:~/dfn/agent-rs (14:27)$ git diff
diff --git a/ic-agent/Cargo.toml b/ic-agent/Cargo.toml
index 8308d2b..5b41a89 100644
--- a/ic-agent/Cargo.toml
+++ b/ic-agent/Cargo.toml
@@ -17,7 +17,7 @@ include = ["src", "Cargo.toml", "../LICENSE", "README.md"]
 [dependencies]
 backoff = "0.4.0"
 cached = { version = "0.46", features = ["ahash"], default-features = false }
-candid = { workspace = true, features = ["value"] }
+candid = { workspace = true }
 ed25519-consensus = { version = "2" }
 futures-util = "0.3.21"
 hex = { workspace = true }
@@ -75,6 +75,7 @@ web-sys = { version = "0.3", features = ["Window"], optional = true }
 
 [dev-dependencies]
 serde_json = "1.0.79"
+dev_candid = { package = "candid", version = "0.10.0", features = ["value"]}
 
 [target.'cfg(not(target_family = "wasm"))'.dev-dependencies]
 tokio = { version = "1.24.2", features = ["full"] }
diff --git a/ic-agent/src/agent/status.rs b/ic-agent/src/agent/status.rs
index e54ea25..a53d2f3 100644
--- a/ic-agent/src/agent/status.rs
+++ b/ic-agent/src/agent/status.rs
@@ -74,8 +74,8 @@ fn can_serilaize_status_as_json() {
 }
 #[test]
 fn can_serialize_status_as_idl() {
-    use candid::types::value::IDLValue;
-    use candid::{Encode, IDLArgs, Result as CandidResult, TypeEnv};
+    use dev_candid::types::value::IDLValue;
+    use dev_candid::{Encode, IDLArgs, Result as CandidResult, TypeEnv};
     let status = Status {
         impl_version: Some("Foo".to_string()),
         replica_health_status: None,
max@sinkpad:~/dfn/agent-rs (14:29)$ 
max@sinkpad:~/dfn/agent-rs (14:32)$ 
max@sinkpad:~/dfn/agent-rs (14:32)$ cargo check
error: the crate `ic-agent v0.31.0 (/home/max/dfn/agent-rs/ic-agent)` depends on crate `candid v0.10.0` multiple times with different names
max@sinkpad:~/dfn/agent-rs (14:38)$ 

[smallstepman]

this worked for me

[bitdivine]

I have looked at the "value" feature and don't really understand the repercussions of adding the feature. It changes some low level behaviour in corner cases. I think that the right answer in this context is to drop the test and not change the feature set. The CandidType and Deserialize traits are pretty well tested elsewhere so it's not likely that they will break here.

[smallstepman]

btw, I don't have strong opinion about adding value feature despite not being used in production code... maybe its ok and not worth the hassle to play the cargo here. Was only trying to be helpful ;)

[bitdivine]

Maybe silly question, but is it necessary to use the alias?

OOh, cool! I didn't know that was possible. Thanks! Yes, I think that is the way to go.

[bitdivine]

Done. CI got stuck. All green now apart from cla, which is hanging. Do you know how to un-stick that?