test: add tests for feedback_arc_set() and feedback_vertex_set()

tests/testthat/test-feedback-sets.R

@@ -0,0 +1,41 @@
+test_that("feedback_arc_set works", {
+  skip_if_no_glpk()
+
+  g <- make_graph(c(1,2, 2,3, 3,1, 4,2, 3,4), directed = TRUE)
+  fas <- feedback_arc_set(g)
+  expect_equal(as.vector(fas), c(2))
+})
+
+test_that("feedback_arc_set works with weights", {
+  skip_if_no_glpk()
+
+  g <- make_ring(4, directed = TRUE)
+  E(g)$weight <- 4:1
+  fas <- feedback_arc_set(g)
+  expect_equal(as.vector(fas), c(4))
+})
+
+test_that("feedback_arc_set works with undirected graphs", {
+  skip_if_no_glpk()
+
+  g <- make_ring(10)
+  fas <- feedback_arc_set(g)
+  expect_equal(length(fas), 1)
+})
+
+test_that("feedback_vertex_set works", {
+  skip_if_no_glpk()
+
+  g <- make_lattice(c(3, 3))
+  fvs <- feedback_vertex_set(g)
+  expect_equal(length(fvs), 2)
+})
+
+test_that("feedback_vertex_set works with weights", {
+  skip_if_no_glpk()
+
+  g <- make_ring(5, directed = TRUE)
+  V(g)$weight <- 5:1
+  fvs <- feedback_vertex_set(g)
+  expect_equal(as.vector(fvs), c(5))
+})