foxhunt/crates/ml/tests/bug28_unused_import_test.rs

#![allow(
    clippy::assertions_on_constants,
    clippy::assertions_on_result_states,
    clippy::clone_on_copy,
    clippy::decimal_literal_representation,
    clippy::doc_markdown,
    clippy::empty_line_after_doc_comments,
    clippy::field_reassign_with_default,
    clippy::get_unwrap,
    clippy::identity_op,
    clippy::inconsistent_digit_grouping,
    clippy::indexing_slicing,
    clippy::integer_division,
    clippy::len_zero,
    clippy::let_underscore_must_use,
    clippy::manual_div_ceil,
    clippy::manual_let_else,
    clippy::manual_range_contains,
    clippy::modulo_arithmetic,
    clippy::needless_range_loop,
    clippy::non_ascii_literal,
    clippy::redundant_clone,
    clippy::shadow_reuse,
    clippy::shadow_same,
    clippy::shadow_unrelated,
    clippy::single_match_else,
    clippy::str_to_string,
    clippy::string_slice,
    clippy::tests_outside_test_module,
    clippy::too_many_lines,
    clippy::unnecessary_wraps,
    clippy::unseparated_literal_suffix,
    clippy::use_debug,
    clippy::useless_vec,
    clippy::wildcard_enum_match_arm,
    clippy::else_if_without_else,
    clippy::expect_used,
    clippy::missing_const_for_fn,
    clippy::similar_names,
    clippy::type_complexity,
    clippy::collapsible_else_if,
    clippy::doc_lazy_continuation,
    clippy::items_after_test_module,
    clippy::map_clone,
    clippy::multiple_unsafe_ops_per_block,
    clippy::unwrap_or_default,
    clippy::assign_op_pattern,
    clippy::needless_borrow,
    clippy::println_empty_string,
    clippy::unnecessary_cast,
    clippy::used_underscore_binding,
    clippy::create_dir,
    clippy::implicit_saturating_sub,
    clippy::exit,
    clippy::expect_fun_call,
    clippy::too_many_arguments,
    clippy::unnecessary_map_or,
    clippy::unwrap_used,
    dead_code,
    unused_imports,
    unused_variables,
    clippy::cloned_ref_to_slice_refs,
    clippy::neg_multiply,
    clippy::while_let_loop,
    clippy::bool_assert_comparison,
    clippy::excessive_precision,
    clippy::trivially_copy_pass_by_ref,
    clippy::op_ref,
    clippy::redundant_closure,
    clippy::unnecessary_lazy_evaluations,
    clippy::if_then_some_else_none,
    clippy::unnecessary_to_owned,
    clippy::single_component_path_imports,
)]
//! Bug #28: Unused import warning for Device in softmax.rs
//!
//! This test ensures ml/src/dqn/softmax.rs compiles without warnings
//! after fixing the conditional compilation of Device import.
//!
//! Post-migration: softmax functions now operate on host &[f32] slices,
//! not on GPU Tensors. No Device import needed.

use ml::dqn::softmax::{softmax_with_temperature, sample_from_softmax, softmax_entropy};

#[test]
fn test_bug28_softmax_imports_clean() {
    // Verify softmax.rs compiles without unused import warnings
    // This test exercises all public functions to ensure they work correctly

    // Test 1: softmax_with_temperature (now takes &[f32] slices)
    let q_values = [1.0f32, 2.0, 3.0];

    let probs = softmax_with_temperature(&q_values, 1.0)
        .expect("Failed to compute softmax");

    // Verify probabilities sum to 1.0
    let sum: f32 = probs.iter().sum();
    assert!(
        (sum - 1.0).abs() < 1e-5,
        "Probabilities should sum to 1.0, got {}",
        sum
    );

    // Test 2: sample_from_softmax
    let action = sample_from_softmax(&q_values, 1.0)
        .expect("Failed to sample action");

    assert!(action < 3, "Action should be in range [0, 3), got {}", action);

    // Test 3: softmax_entropy
    let entropy = softmax_entropy(&q_values, 1.0)
        .expect("Failed to compute entropy");

    assert!(entropy > 0.0, "Entropy should be positive, got {}", entropy);
    assert!(entropy < 2.0, "Entropy should be < log2(3) ~= 1.585, got {}", entropy);
}

#[test]
fn test_bug28_softmax_numerical_stability() {
    // Test the log-sum-exp trick for numerical stability

    // Large Q-values that would overflow without stability trick
    let q_values = [100.0f32, 200.0, 300.0];

    let probs = softmax_with_temperature(&q_values, 1.0)
        .expect("Failed to compute softmax with large values");

    // Should still sum to 1.0 despite large values
    let sum: f32 = probs.iter().sum();
    assert!(
        (sum - 1.0).abs() < 1e-5,
        "Probabilities should sum to 1.0 even with large Q-values, got {}",
        sum
    );

    // Verify no NaN or Inf
    assert!(probs.iter().all(|&p| p.is_finite()), "All probabilities should be finite");
}

#[test]
fn test_bug28_temperature_control() {
    // Test temperature parameter effect on exploration
    let q_values = [1.0f32, 2.0, 3.0];

    // Low temperature (greedy)
    let entropy_low = softmax_entropy(&q_values, 0.1)
        .expect("Failed to compute entropy with low temp");

    // High temperature (exploratory)
    let entropy_high = softmax_entropy(&q_values, 10.0)
        .expect("Failed to compute entropy with high temp");

    // High temperature should produce higher entropy
    assert!(
        entropy_high > entropy_low,
        "High temperature ({}) should produce higher entropy than low temperature ({})",
        entropy_high,
        entropy_low
    );
}