From be6845beaa503b06a192f7275c39a48454221781 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Tue, 1 Oct 2024 14:28:12 +0200
Subject: [PATCH] feat: add error when both `graph_from_biadjacency()`'s
 arguments `multiple` and `weighted` are TRUE

---
 R/incidence.R                      | 7 +++++++
 tests/testthat/_snaps/incidence.md | 9 +++++++++
 tests/testthat/test-incidence.R    | 3 +++
 3 files changed, 19 insertions(+)

diff --git a/R/incidence.R b/R/incidence.R
index 6471af0a38..49120ba4dd 100644
--- a/R/incidence.R
+++ b/R/incidence.R
@@ -218,6 +218,13 @@ graph_from_biadjacency_matrix <- function(incidence, directed = FALSE,
 
   if (!is.null(weighted)) {
     if (is.logical(weighted) && weighted) {
+
+      if (multiple) {
+        cli::cli_abort(c(
+          "{.arg multiple} and {.arg weighted} cannot be both {.code TRUE}.",
+          "igraph either interprets numbers larger than 1 as weights or as multiplicities, but it cannot be both."
+        ))
+      }
       weighted <- "weight"
     }
     if (is.logical(weighted) && !weighted) {
diff --git a/tests/testthat/_snaps/incidence.md b/tests/testthat/_snaps/incidence.md
index ed8636ccef..b15badd95f 100644
--- a/tests/testthat/_snaps/incidence.md
+++ b/tests/testthat/_snaps/incidence.md
@@ -76,3 +76,12 @@
       ! `weighted` can't be a number.
       i See `?graph_from_biadjacency_matrix()`'s manual page.
 
+---
+
+    Code
+      (g <- graph_from_biadjacency_matrix(inc, multiple = TRUE, weighted = TRUE))
+    Condition
+      Error in `graph_from_biadjacency_matrix()`:
+      ! `multiple` and `weighted` cannot be both `TRUE`.
+      igraph either interprets numbers larger than 1 as weights or as multiplicities, but it cannot be both.
+
diff --git a/tests/testthat/test-incidence.R b/tests/testthat/test-incidence.R
index 73d0efaff5..7b871739e1 100644
--- a/tests/testthat/test-incidence.R
+++ b/tests/testthat/test-incidence.R
@@ -165,4 +165,7 @@ test_that("graph_from_biadjacency_matrix() errors well", {
   expect_snapshot(error = TRUE, {
     (g <- graph_from_biadjacency_matrix(inc, weight = 42))
   })
+  expect_snapshot(error = TRUE, {
+    (g <- graph_from_biadjacency_matrix(inc, multiple = TRUE, weighted = TRUE))
+  })
 })