feat(humantime): add support for Option<Duration> with serde_humantime

[tenuous-guidance]

Whilst Duration itself has an Option builder, which serde_humantime already handles, Option uses OptionBuilder, which serde_humantime does not support

Summary by CodeRabbit

• New Features

  • Added an optional "humantime" feature to enable human-readable duration support in config parsing.

• Tests

  • Added tests covering parsing of human-readable duration strings.

• Documentation

  • Updated changelog with usage example for the new humantime feature.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds an optional humantime feature to confik that wires in humantime-serde, exposes a conditional public re-export, and provides serde helpers for Option<Duration> with accompanying tests and changelog entry.

Changes

Cohort / File(s)	Summary
Feature / Manifest confik/Cargo.toml	Added humantime feature mapping to dep:humantime-serde; declared humantime-serde as an optional dependency and as a dev-dependency (v1).
Public API / Re-exports confik/src/lib.rs	Added #[cfg(feature = "humantime")] pub use self::third_party::humantime; to conditionally expose the humantime helpers.
humantime helpers confik/src/third_party.rs	Added pub mod humantime (behind humantime feature) with option submodule providing serialize and deserialize functions for OptionBuilder<Option<Duration>> that delegate to humantime_serde helpers.
Tests confik/tests/third_party.rs	Added feature-gated test (humantime + toml) that parses timeout = "1h 42m" and asserts the resulting Duration (6120s).
Changelog confik/CHANGELOG.md	Added Unreleased entry documenting the new confik::humantime serde helpers and usage example.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐇 I hopped through crates and feature trees,
Found humantime hiding in Cargo keys.
Option by option, durations now play,
Serde sings seconds in a friendly display.
— a small rabbit, testing all day 🥕✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding support for Option serialization with serde_humantime through a new humantime feature flag.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch option-humantime-serde

📝 Coding Plan

• Generate coding plan for human review comments

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

Tip

CodeRabbit can enforce grammar and style rules using `languagetool`.

Configure the reviews.tools.languagetool setting to enable/disable rules and categories. Refer to the LanguageTool Community to learn more.

[coderabbitai]

🧹 Nitpick comments (1)

confik/tests/third_party.rs (1)

7-26: Test coverage is limited to the happy path.

The test validates parsing a present duration value but doesn't cover:

• Missing timeout field (should result in None)
• Behavior when the field is explicitly absent

Consider adding test cases for these scenarios to ensure the OptionBuilder handling works correctly for all cases.

🧪 Suggested additional test cases

#[test]
fn from_humantime_option_missing() {
    #[derive(Debug, PartialEq, Eq, Configuration)]
    struct Config {
        #[confik(forward(serde(with = "confik::humantime::option")))]
        timeout: Option<Duration>,
    }

    let config = ConfigBuilder::<Config>::default()
        .override_with(TomlSource::new(""))
        .try_build()
        .unwrap();

    assert_eq!(config, Config { timeout: None });
}

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@confik/tests/third_party.rs` around lines 7 - 26, Add negative-path tests for
the humantime option handling: create tests named like
from_humantime_option_missing and from_humantime_option_explicit_none that use
the same Config struct (with #[confik(forward(serde(with =
"confik::humantime::option")))] timeout: Option<Duration>) and build via
ConfigBuilder::<Config>::default().override_with(TomlSource::new(...)).try_build().unwrap();
for the missing case pass an empty source ("" ) and assert Config { timeout:
None }, and for the explicit-absent case pass a TOML that sets timeout = none
(or deletes the key) and assert None; add these new tests alongside
from_humantime_option to ensure OptionBuilder and the serde wrapper handle
absent/explicit-null correctly.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@confik/tests/third_party.rs`:
- Around line 7-26: Add negative-path tests for the humantime option handling:
create tests named like from_humantime_option_missing and
from_humantime_option_explicit_none that use the same Config struct (with
#[confik(forward(serde(with = "confik::humantime::option")))] timeout:
Option<Duration>) and build via
ConfigBuilder::<Config>::default().override_with(TomlSource::new(...)).try_build().unwrap();
for the missing case pass an empty source ("" ) and assert Config { timeout:
None }, and for the explicit-absent case pass a TOML that sets timeout = none
(or deletes the key) and assert None; add these new tests alongside
from_humantime_option to ensure OptionBuilder and the serde wrapper handle
absent/explicit-null correctly.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: c698f400-f4c8-4df5-9bb8-e48b55740000

📥 Commits

Reviewing files that changed from the base of the PR and between 95a47bb and c94b381.

📒 Files selected for processing (5)

• confik/CHANGELOG.md
• confik/Cargo.toml
• confik/src/lib.rs
• confik/src/third_party.rs
• confik/tests/third_party.rs

✅ Files skipped from review due to trivial changes (1)

• confik/CHANGELOG.md

🚧 Files skipped from review as they are similar to previous changes (1)

• confik/Cargo.toml