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//! Generic fetch-state machine for data tabs.
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/// Lifecycle of a data-tab fetch request.

            

        

            

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///

            

        

            

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/// Transitions: `Idle` → `Loading` (on submit) → `Loaded` or `Error` (on reply).

            

        

            

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/// A `refresh` resets back to `Idle` so the next `switch_tab` re-fetches.

            

        

            

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#[derive(Debug, Clone, PartialEq)]

            

        

            

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pub enum Fetch<T> {

            

        

            

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    /// No request has been issued yet (initial state or after reset).

            

        

            

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    Idle,

            

        

            

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    /// A request was issued with the given envelope id; reply is pending.

            

        

            

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    Loading { id: i64 },

            

        

            

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    /// Reply received and parsed successfully.

            

        

            

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    Loaded(T),

            

        

            

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    /// Reply received but produced an error.

            

        

            

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    Error(String),

            

        

            

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}

            

        

            

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#[cfg(test)]

            

        

            

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mod tests {

            

        

            

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    use super::*;

            

        

            

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    #[test]

            

        

            

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    fn idle_is_default_variant() {

            

        

            

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        let f: Fetch<Vec<String>> = Fetch::Idle;

            

        

            

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        assert!(matches!(f, Fetch::Idle));

            

        

            

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    }

            

        

            

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    #[test]

            

        

            

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    fn loading_carries_id() {

            

        

            

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        let f: Fetch<()> = Fetch::Loading { id: 7 };

            

        

            

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        assert!(matches!(f, Fetch::Loading { id: 7 }));

            

        

            

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    }

            

        

            

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    #[test]

            

        

            

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    fn loaded_carries_data() {

            

        

            

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        let f = Fetch::Loaded(vec![1u32, 2, 3]);

            

        

            

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        assert!(matches!(f, Fetch::Loaded(_)));

            

        

            

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        if let Fetch::Loaded(v) = f {

            

        

            

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            assert_eq!(v.len(), 3);

            

        

            

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        }

            

        

            

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    }

            

        

            

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    #[test]

            

        

            

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    fn error_carries_message() {

            

        

            

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        let f: Fetch<()> = Fetch::Error("oops".into());

            

        

            

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        assert!(matches!(f, Fetch::Error(ref s) if s == "oops"));

            

        

            

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    }

            

        

            

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    #[test]

            

        

            

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    fn clone_eq_roundtrip() {

            

        

            

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        let a: Fetch<()> = Fetch::Loading { id: 42 };

            

        

            

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        let b = a.clone();

            

        

            

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        assert_eq!(a, b);

            

        

            

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    }

            

        

            

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}