card-test

card-test — the canonical cast-pipeline test recipe

This skill gives ONE rigid recipe for runtime engine tests that cast a spell and assert its effect. It exists because six test-harness foot-guns recur; the [SpellCast] driver and [CastOutcome] (in crates/engine/src/game/scenario.rs) make them structurally impossible when you follow this recipe.

Reference ports that demonstrate the pattern:

• crates/engine/tests/chord_of_calling.rs — X-spell, convoke, final_waiting_for() boundary.
• crates/engine/src/game/casting.rs — exsanguinate_* (life deltas, 2- and 3-player), vicious_rivalry_* (X-cost filter + zones), kozileks_command_modes_* (modal + X + multi-target).

The recipe

use engine::game::scenario::{GameScenario, GameRunner};
// ... typed imports for the effect under test ...

#[test]
fn my_card_does_the_thing() {
    // 1. BUILD STATE via GameScenario (or wrap a raw GameState with
    //    GameRunner::from_state(state) when the test builds state imperatively).
    let mut scenario = GameScenario::new();
    scenario.at_phase(Phase::PreCombatMain);
    let spell = scenario
        .add_spell_to_hand_from_oracle(P0, "My Card", /* is_instant */ true, ORACLE)
        .id();
    // ... stage targets / mana / library as needed ...
    let mut runner = scenario.build();

    // 2. CAST through the pipeline. Declare INTENT, never targets-by-hand.
    let outcome = runner
        .cast(spell)
        .modes(&[0, 2])              // modal "choose N" — omit if non-modal
        .x(3)                        // announce X — omit if non-X
        .target_player(P1)           // declare a player intent (reusable across slots)
        .target_objects(&[victim])   // declare object intents (one per slot, in order)
        .convoke_with(&[creature])   // tap creatures to pay via Convoke — omit otherwise
        .resolve();

    // 3. ASSERT via CastOutcome deltas — behavior/semantics, never AST internals.
    outcome.assert_life_delta(P1, -3);
    outcome.assert_zone(&[victim], Zone::Exile);
    outcome.assert_hand_drawn(P0, 1);
    // For "no further prompt" boundaries (e.g. fail-to-find), inspect the halt state:
    assert!(matches!(outcome.final_waiting_for(), WaitingFor::Priority { .. }));
}