test: improve test-dot.product.game, fold into test-games (#1705)

Co-authored-by: David Schoch <[email protected]>

tests/testthat/test-games.R

@@ -603,3 +603,65 @@ test_that("HSBM with list arguments works", {
   )
   expect_equal(g_hsbm5[] + g_hsbm7[], g_hsbm8[])
 })
+
+test_that("Dot product rng works", {
+  withr::local_seed(42)
+  vecs <- cbind(
+    c(0, 1, 1, 1, 0) / 3, c(0, 1, 1, 0, 1) / 3, c(1, 1, 1, 1, 0) / 4,
+    c(0, 1, 1, 1, 0)
+  )
+
+  g <- sample_dot_product(vecs)
+  g0 <- graph_from_literal(1:2:3 - 4)
+  expect_equal(as.matrix(g[]), as.matrix(g0[]), ignore_attr = TRUE)
+
+  vecs <- replicate(5, rep(1 / 2, 4))
+  g <- sample_dot_product(vecs)
+  expect_equal(g[], make_full_graph(5)[], ignore_attr = TRUE)
+
+  g2 <- sample_dot_product(vecs, directed = TRUE)
+  expect_equal(g2[], make_full_graph(5, directed = TRUE)[], ignore_attr = TRUE)
+
+  vecs <- replicate(100, rep(sqrt(1 / 8), 4))
+  g <- sample_dot_product(vecs)
+  expect_ecount(g, 2451)
+
+  g2 <- sample_dot_product(vecs, directed = TRUE)
+  expect_ecount(g2, 4941)
+})
+
+test_that("sample_dot_product generates edges with correct probabilities", {
+  withr::local_seed(42)
+  latent_features <- cbind(
+    c(0, 1, 1, 1, 0) / 3, c(0, 1, 1, 0, 1) / 3, c(1, 1, 1, 1, 0) / 4,
+    c(0, 1, 1, 1, 0)
+  )
+  expected_probs <- t(latent_features)%*%latent_features
+  diag(expected_probs) <- 0
+  num_graphs <- 1000
+  edge_counts <- matrix(0, nrow = 4, ncol = 4)
+
+  for (i in seq_len(num_graphs)) {
+    g <- sample_dot_product(latent_features)
+    adj_matrix <- as_adjacency_matrix(g, sparse = FALSE)
+    edge_counts <- edge_counts + adj_matrix
+  }
+  empirical_probs <- edge_counts / num_graphs
+  diag(empirical_probs) <- 0
+  tolerance <- 0.05
+  expect_true(all(abs(empirical_probs - expected_probs) < tolerance))
+})
+
+test_that("Dot product rng gives warnings", {
+  vecs <- cbind(c(1, 1, 1) / 3, -c(1, 1, 1) / 3)
+  expect_warning(
+    g <- sample_dot_product(vecs),
+    "Negative connection probability in dot-product graph"
+  )
+
+  vecs <- cbind(c(1, 1, 1), c(1, 1, 1))
+  expect_warning(
+    g <- sample_dot_product(vecs),
+    paste0("Greater than 1 connection probability ", "in dot-product graph")
+  )
+})