008 complex flow test

// Test: Complex flow with chained events and mocks
//
// This is the REAL test of the testing framework:
// - Real program events defined outside tests
// - Subflow chains multiple events together
// - Tests mock impure events, call real flows
// - Pure events called directly (no mock needed)

~import std/testing

// ============================================
// THE ACTUAL PROGRAM
// ============================================

// Database layer (impure - external DB)
~event db.get-user { id: u32 }
| found { id: u32, balance: u32 }
| not-found

// Payment service (impure - external API)
~event payment.charge { user_id: u32, amount: u32 }
| success []const u8
| failed []const u8

// Pure validation (no side effects)
~event validate.amount { amount: u32, balance: u32 }
| valid
| insufficient

~[pure] proc validate.amount|zig {
    if (amount <= balance) {
        return .{ .valid = .{} };
    } else {
        return .{ .insufficient = .{} };
    }
}

// The main flow - chains everything together
~event process-payment { user_id: u32, amount: u32 }
| success []const u8
| user-not-found
| insufficient-funds

~process-payment = db.get-user(id: user_id)
| found u |> validate.amount(amount, u.balance)
    | valid |> payment.charge(user_id: u.id, amount)
        | success tx => success tx
        | failed _ => insufficient-funds
    | insufficient => insufficient-funds
| not-found => user-not-found

// ============================================
// THE TESTS
// ============================================

~test(Successful payment) {
    ~db.get-user => found { id: 42, balance: 100 }
    ~payment.charge => success "tx123"

    ~process-payment(user_id: 42, amount: 50)
    | success s |> assert(s.len == 5)  // "tx123" has 5 chars
}

~test(Insufficient funds rejected) {
    ~db.get-user => found { id: 42, balance: 30 }

    ~process-payment(user_id: 42, amount: 50)
    | insufficient-funds |> assert.ok()
}

~test(User not found) {
    ~db.get-user => not-found

    ~process-payment(user_id: 999, amount: 50)
    | user-not-found |> assert.ok()
}