tincan 0.3.0

A lightweight reactive state management library for Rust.
Documentation 
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use std::cell::Cell;
use std::rc::Rc;
use tincan::Scope;

#[test]
fn test_scope_isolation() {
    let cx1 = Scope::new();
    let cx2 = Scope::new();

    let signal1 = cx1.signal(1);
    let signal2 = cx2.signal(2);

    assert_eq!(signal1.get(), 1);
    assert_eq!(signal2.get(), 2);

    signal1.set(10);
    signal2.set(20);

    assert_eq!(signal1.get(), 10);
    assert_eq!(signal2.get(), 20);
}

#[test]
fn test_scope_cleanup() {
    let run_count = Rc::new(Cell::new(0));

    {
        let cx = Scope::new();
        let count = cx.signal(0);

        let count_clone = count.clone();
        let run_count_clone = Rc::clone(&run_count);
        let _effect = cx.effect(move || {
            let _ = count_clone.get();
            run_count_clone.set(run_count_clone.get() + 1);
        });

        assert_eq!(run_count.get(), 1);
        count.set(5);
        assert_eq!(run_count.get(), 2);
    } // Scope dropped

    // Effect should not run anymore
    assert_eq!(run_count.get(), 2);
}

#[test]
fn test_scope_clear() {
    let cx = Scope::new();
    let signal = cx.signal(42);

    assert_eq!(signal.get(), 42);

    cx.clear();

    // Signal still works but dependencies are cleared
    signal.set(100);
    assert_eq!(signal.get(), 100);
}

#[test]
fn test_scope_default() {
    let cx = Scope::default();
    let signal = cx.signal(42);
    assert_eq!(signal.get(), 42);
}

#[test]
fn test_nested_scopes() {
    let outer_cx = Scope::new();
    let outer_signal = outer_cx.signal(1);

    {
        let inner_cx = Scope::new();
        let inner_signal = inner_cx.signal(2);

        assert_eq!(outer_signal.get(), 1);
        assert_eq!(inner_signal.get(), 2);

        inner_signal.set(20);
        assert_eq!(inner_signal.get(), 20);
    }

    assert_eq!(outer_signal.get(), 1);
    outer_signal.set(10);
    assert_eq!(outer_signal.get(), 10);
}

#[test]
fn test_scope_with_many_signals() {
    let cx = Scope::new();
    let signals: Vec<_> = (0..100).map(|i| cx.signal(i)).collect();

    for (i, signal) in signals.iter().enumerate() {
        assert_eq!(signal.get(), i);
    }

    for (i, signal) in signals.iter().enumerate() {
        signal.set(i * 2);
    }

    for (i, signal) in signals.iter().enumerate() {
        assert_eq!(signal.get(), i * 2);
    }
}

#[test]
fn test_scope_with_many_effects() {
    let cx = Scope::new();
    let signal = cx.signal(0);
    let counters: Vec<_> = (0..10).map(|_| Rc::new(Cell::new(0))).collect();

    let _effects: Vec<_> = counters
        .iter()
        .map(|counter| {
            let signal_clone = signal.clone();
            let counter_clone = Rc::clone(counter);
            cx.effect(move || {
                let _ = signal_clone.get();
                counter_clone.set(counter_clone.get() + 1);
            })
        })
        .collect();

    // All effects run immediately
    for counter in &counters {
        assert_eq!(counter.get(), 1);
    }

    signal.set(5);

    // All effects run again
    for counter in &counters {
        assert_eq!(counter.get(), 2);
    }
}

#[test]
fn test_complex_dependency_graph() {
    let cx = Scope::new();

    // Create a diamond dependency graph
    let root = cx.signal(1);

    let left = cx.memo({
        let root = root.clone();
        move || root.get() * 2
    });

    let right = cx.memo({
        let root = root.clone();
        move || root.get() * 3
    });

    let bottom = cx.memo({
        let left = left.clone();
        let right = right.clone();
        move || left.get() + right.get()
    });

    assert_eq!(bottom.get(), 5); // 2 + 3

    root.set(2);
    assert_eq!(bottom.get(), 10); // 4 + 6

    root.set(10);
    assert_eq!(bottom.get(), 50); // 20 + 30
}

#[test]
fn test_deep_dependency_chain() {
    let cx = Scope::new();
    let input = cx.signal(1);

    let mut current = input.clone().map(|x| *x);

    // Create a chain of 10 derived signals
    for _ in 0..10 {
        current = current.map(|x| *x + 1);
    }

    assert_eq!(current.get(), 11); // 1 + 10

    input.set(5);
    assert_eq!(current.get(), 15); // 5 + 10
}

#[test]
fn test_wide_dependency_graph() {
    let cx = Scope::new();
    let root = cx.signal(10);

    // Create 20 derived signals from the same root
    let derived: Vec<_> = (0..20)
        .map(|i| {
            let root = root.clone();
            cx.memo(move || root.get() + i)
        })
        .collect();

    for (i, memo) in derived.iter().enumerate() {
        assert_eq!(memo.get(), 10 + i);
    }

    root.set(100);

    for (i, memo) in derived.iter().enumerate() {
        assert_eq!(memo.get(), 100 + i);
    }
}

#[test]
fn test_memo_deduplication() {
    let cx = Scope::new();
    let a = cx.signal(1);
    let b = cx.signal(1);
    let compute_count = Rc::new(Cell::new(0));

    // Memo depends on both a and b
    let sum = cx.memo({
        let a = a.clone();
        let b = b.clone();
        let compute_count = Rc::clone(&compute_count);
        move || {
            compute_count.set(compute_count.get() + 1);
            a.get() + b.get()
        }
    });

    assert_eq!(sum.get(), 2);
    assert_eq!(compute_count.get(), 1);

    // Change a to same value as b - sum shouldn't change
    a.set(1);
    assert_eq!(sum.get(), 2);
    // Memo still recomputes (it doesn't track value changes, only dependency changes)
    assert_eq!(compute_count.get(), 2);

    // Change to different value
    a.set(5);
    assert_eq!(sum.get(), 6);
    assert_eq!(compute_count.get(), 3);
}

#[test]
fn test_circular_update_prevention() {
    let cx = Scope::new();
    let a = cx.signal(0);
    let b = cx.signal(0);
    let update_count = Rc::new(Cell::new(0));

    let a_clone = a.clone();
    let b_clone = b.clone();
    let update_count_clone = Rc::clone(&update_count);
    let _effect = cx.effect(move || {
        let count = update_count_clone.get();
        update_count_clone.set(count + 1);

        // Prevent infinite loop by limiting updates
        if count < 10 {
            let val_a = a_clone.get();
            if val_a < 5 {
                b_clone.set(val_a + 1);
            }
        }
    });

    a.set(1);

    // Should have run multiple times but not infinitely
    assert!(update_count.get() > 1);
    assert!(update_count.get() <= 10);
}

#[test]
fn test_signal_map_propagation() {
    let cx = Scope::new();
    let base = cx.signal(10);
    let doubled = base.map(|x| x * 2);
    let tripled = doubled.map(|x| x + 10);

    assert_eq!(tripled.get(), 30); // 10 * 2 + 10

    base.set(20);
    assert_eq!(tripled.get(), 50); // 20 * 2 + 10
}

#[test]
fn test_multiple_watchers() {
    let cx = Scope::new();
    let signal = cx.signal(0);

    let count1 = Rc::new(Cell::new(0));
    let count2 = Rc::new(Cell::new(0));
    let count3 = Rc::new(Cell::new(0));

    let count1_clone = Rc::clone(&count1);
    let _guard1 = signal.watch(move |_| {
        count1_clone.set(count1_clone.get() + 1);
    });

    let count2_clone = Rc::clone(&count2);
    let _guard2 = signal.watch(move |_| {
        count2_clone.set(count2_clone.get() + 1);
    });

    let count3_clone = Rc::clone(&count3);
    let _guard3 = signal.watch(move |_| {
        count3_clone.set(count3_clone.get() + 1);
    });

    assert_eq!(count1.get(), 1);
    assert_eq!(count2.get(), 1);
    assert_eq!(count3.get(), 1);

    signal.set(5);

    assert_eq!(count1.get(), 2);
    assert_eq!(count2.get(), 2);
    assert_eq!(count3.get(), 2);
}

#[test]
fn test_scope_stress_test() {
    let cx = Scope::new();

    // Create a complex graph
    let inputs: Vec<_> = (0..10).map(|i| cx.signal(i)).collect();

    let memos: Vec<_> = inputs
        .iter()
        .map(|input| {
            let input = input.clone();
            cx.memo(move || input.get() * 2)
        })
        .collect();

    let sum = cx.memo({
        let memos = memos.clone();
        move || memos.iter().map(|m| m.get()).sum::<i32>()
    });

    assert_eq!(sum.get(), 90); // 0*2 + 1*2 + ... + 9*2 = 90

    // Update all inputs
    for (i, input) in inputs.iter().enumerate() {
        input.set((i * 2) as i32);
    }

    assert_eq!(sum.get(), 180); // 0*2 + 2*2 + 4*2 + ... + 18*2 = 180
}

#[test]
fn test_empty_scope() {
    let cx = Scope::new();
    // Just create a scope and drop it - should not panic
    drop(cx);
}

#[test]
fn test_signal_with_large_value() {
    let cx = Scope::new();
    let large_vec: Vec<i32> = (0..10000).collect();
    let signal = cx.signal(large_vec.clone());

    assert_eq!(signal.get(), large_vec);

    let new_vec: Vec<i32> = (0..10000).map(|x| x * 2).collect();
    signal.set(new_vec.clone());

    assert_eq!(signal.get(), new_vec);
}

#[test]
fn test_concurrent_scope_independence() {
    let cx1 = Scope::new();
    let cx2 = Scope::new();

    let sig1 = cx1.signal(1);
    let sig2 = cx2.signal(2);

    let run1 = Rc::new(Cell::new(0));
    let run2 = Rc::new(Cell::new(0));

    let sig1_clone = sig1.clone();
    let run1_clone = Rc::clone(&run1);
    let _effect1 = cx1.effect(move || {
        let _ = sig1_clone.get();
        run1_clone.set(run1_clone.get() + 1);
    });

    let sig2_clone = sig2.clone();
    let run2_clone = Rc::clone(&run2);
    let _effect2 = cx2.effect(move || {
        let _ = sig2_clone.get();
        run2_clone.set(run2_clone.get() + 1);
    });

    assert_eq!(run1.get(), 1);
    assert_eq!(run2.get(), 1);

    sig1.set(10);
    assert_eq!(run1.get(), 2);
    assert_eq!(run2.get(), 1); // Should not change

    sig2.set(20);
    assert_eq!(run1.get(), 2); // Should not change
    assert_eq!(run2.get(), 2);
}