Add reliability weighting test

tests/testthat/test-contrast_rsa_model.R

@@ -750,3 +750,89 @@ test_that("contrast_rsa_model output metrics are internally consistent", {
   beta_delta_rel <- run_metric("beta_delta_reliable", reliability = TRUE)
   expect_equal(beta_delta_rel, beta_delta_vec * rho_const, tolerance = 1e-6)
 })
+
+test_that("beta_delta_reliable uses reliability weights from fold deltas", {
+  dset <- mock_mvpa_dataset_train(n_samples = 8, n_cond = 4, n_blocks = 2, n_voxels = 1)
+  colnames(dset$train_data) <- "V1"
+  mvpa_des <- dset$design
+
+  C_custom <- matrix(c(
+    1, 0,
+    0, 1,
+    0, 0,
+    0, 0
+  ), nrow = 4, ncol = 2, byrow = TRUE,
+  dimnames = list(levels(mvpa_des$Y), c("Con1", "Con2")))
+
+  ms_des <- msreve_design(mvpa_des, C_custom)
+
+  model_spec <- contrast_rsa_model(
+    dataset = dset,
+    design = ms_des,
+    regression_type = "pearson",
+    output_metric = c("beta_delta_reliable"),
+    calc_reliability = TRUE,
+    check_collinearity = FALSE
+  )
+
+  cv_spec <- mock_cv_spec_s3(mvpa_des)
+  sl_data <- dset$train_data
+  sl_info <- list(center_local_id = 1, center_global_id = 1, radius = 0, n_voxels = 1)
+
+  fold_estimates_mock <- array(0, dim = c(4, 1, 2),
+    dimnames = list(levels(mvpa_des$Y), "V1", c("Fold1", "Fold2")))
+  fold_estimates_mock[, 1, 1] <- c(1, 0, 0, 0)
+  fold_estimates_mock[, 1, 2] <- c(2, 0, 0, 0)
+  mean_estimate_mock <- apply(fold_estimates_mock, c(1, 2), mean)
+
+  Delta1 <- t(fold_estimates_mock[, , 1]) %*% C_custom
+  Delta2 <- t(fold_estimates_mock[, , 2]) %*% C_custom
+  deltas <- rbind(Delta1[1, ], Delta2[1, ])
+  mean_delta <- c(0, 0)
+  M2_delta <- c(0, 0)
+  valid_folds <- 0
+  for (i in seq_len(nrow(deltas))) {
+    delta_fold <- deltas[i, ]
+    if (anyNA(delta_fold)) next
+    valid_folds <- valid_folds + 1
+    delta_diff <- delta_fold - mean_delta
+    mean_delta <- mean_delta + delta_diff / valid_folds
+    M2_delta <- M2_delta + delta_diff * (delta_fold - mean_delta)
+  }
+  rho_expected <- rep(1, ncol(C_custom))
+  if (valid_folds > 1) {
+    var_delta <- M2_delta / (valid_folds - 1)
+    sigma2_noise_param <- (valid_folds - 1) * var_delta
+    denom <- var_delta + sigma2_noise_param
+    rho_expected <- ifelse(denom < 1e-10, 1, sigma2_noise_param / denom)
+    rho_expected[is.na(rho_expected)] <- 0
+  } else if (valid_folds == 1) {
+    rho_expected[M2_delta == 0] <- 1
+    rho_expected[M2_delta != 0] <- 0
+  } else {
+    rho_expected <- rep(0, ncol(C_custom))
+  }
+
+  beta_mock <- c(2, 1)
+
+  result <- with_mocked_bindings(
+    compute_crossvalidated_means_sl = function(...) {
+      list(mean_estimate = mean_estimate_mock, fold_estimates = fold_estimates_mock)
+    },
+    run_cor = function(dvec, obj) {
+      setNames(beta_mock, colnames(obj$design$model_mat))
+    },
+    .package = "rMVPA",
+    {
+      train_model.contrast_rsa_model(model_spec, sl_data, sl_info, cv_spec)
+    }
+  )
+
+  Delta_sl <- t(mean_estimate_mock) %*% C_custom
+  delta_vc_sl <- Delta_sl[1, ]
+  beta_delta_expected <- beta_mock * delta_vc_sl
+
+  expect_equal(result$beta_delta_reliable,
+               beta_delta_expected * rho_expected,
+               tolerance = 1e-6)
+})