Add additional functions to uniffi-fixture-time (#1489)

`to_string_timestamp` and `get_pre_epoch_timestamp` separate 2-way back
and forth conversion process, making it possible to test 1-way
conversion.

`to_string_timestamp` ensures that foreign language bindings lower the
timestamp correctly, and that foreign language bindings interpret the
timestamp the same way that Rust does.

`get_pre_epoch_timestamp` ensures that foreign language bindings lift
the timestamp correctly, and that Rust interprets the timestamp the same
way that foreign language bindings do.

fixtures/uniffi-fixture-time/Cargo.toml

@@ -13,6 +13,7 @@ name = "uniffi_chronological"
 [dependencies]
 uniffi = {path = "../../uniffi"}
 thiserror = "1.0"
+chrono = { version = "0.4.23", default-features = false, features = ["alloc", "std"] }
 
 [build-dependencies]
 uniffi = {path = "../../uniffi", features = ["build"] }

fixtures/uniffi-fixture-time/src/chronological.udl

@@ -5,6 +5,16 @@ enum ChronologicalError {
 };
 
 namespace chronological {
+ [Throws=ChronologicalError]
+ timestamp return_timestamp(timestamp a);
+
+ [Throws=ChronologicalError]
+ duration return_duration(duration a);
+
+ string to_string_timestamp(timestamp a);
+
+ timestamp get_pre_epoch_timestamp();
+
  [Throws=ChronologicalError]
  timestamp add(timestamp a, duration b);
 

fixtures/uniffi-fixture-time/src/lib.rs

@@ -4,6 +4,9 @@
 
 use std::time::{Duration, SystemTime};
 
+use chrono::offset::Utc;
+use chrono::DateTime;
+
 #[derive(Debug, thiserror::Error)]
 pub enum ChronologicalError {
  #[error("Time overflow on an operation with {a:?} and {b:?}")]
@@ -12,6 +15,25 @@ pub enum ChronologicalError {
  TimeDiffError { a: SystemTime, b: SystemTime },
 }
 
+fn return_timestamp(a: SystemTime) -> Result<SystemTime> {
+ Ok(a)
+}
+
+fn return_duration(a: Duration) -> Result<Duration> {
+ Ok(a)
+}
+
+fn to_string_timestamp(a: SystemTime) -> String {
+ let datetime: DateTime<Utc> = a.into();
+ datetime.format("%Y-%m-%dT%H:%M:%S.%fZ").to_string()
+}
+
+fn get_pre_epoch_timestamp() -> SystemTime {
+ std::time::SystemTime::UNIX_EPOCH
+ .checked_sub(std::time::Duration::new(1, 1_000_000))
+ .unwrap()
+}
+
 fn add(a: SystemTime, b: Duration) -> Result<SystemTime> {
  a.checked_add(b)
  .ok_or(ChronologicalError::TimeOverflow { a, b })