diff --git a/tests/testthat/test-average.path.length.R b/tests/testthat/test-average.path.length.R
deleted file mode 100644
index 5a40827e6f3..00000000000
--- a/tests/testthat/test-average.path.length.R
+++ /dev/null
@@ -1,69 +0,0 @@
-test_that("mean_distance works", {
-  apl <- function(graph) {
-    sp <- distances(graph, mode = "out")
-    if (is_directed(graph)) {
-      diag(sp) <- NA
-    } else {
-      sp[lower.tri(sp, diag = TRUE)] <- NA
-    }
-    sp[sp == "Inf"] <- NA
-    mean(sp, na.rm = TRUE)
-  }
-
-  giant.component <- function(graph, mode = "weak") {
-    clu <- components(graph, mode = mode)
-    induced_subgraph(graph, which(clu$membership == which.max(clu$csize)))
-  }
-
-  g <- giant.component(sample_gnp(100, 3 / 100))
-  expect_equal(apl(g), mean_distance(g))
-
-  g <- giant.component(sample_gnp(100, 6 / 100, directed = TRUE), mode = "strong")
-  expect_equal(apl(g), mean_distance(g))
-
-  g <- sample_gnp(100, 2 / 100)
-  expect_equal(apl(g), mean_distance(g))
-
-  g <- sample_gnp(100, 4 / 100, directed = TRUE)
-  expect_equal(apl(g), mean_distance(g))
-})
-
-test_that("mean_distance works correctly for disconnected graphs", {
-  g <- make_full_graph(5) %du% make_full_graph(7)
-  md <- mean_distance(g, unconnected = FALSE)
-  expect_equal(Inf, md)
-  md <- mean_distance(g, unconnected = TRUE)
-  expect_equal(1, md)
-})
-
-test_that("mean_distance can provide details", {
-  apl <- function(graph) {
-    sp <- distances(graph, mode = "out")
-    if (is_directed(graph)) {
-      diag(sp) <- NA
-    } else {
-      sp[lower.tri(sp, diag = TRUE)] <- NA
-    }
-    sp[sp == "Inf"] <- NA
-    mean(sp, na.rm = TRUE)
-  }
-
-  giant.component <- function(graph, mode = "weak") {
-    clu <- components(graph, mode = mode)
-    induced_subgraph(graph, which(clu$membership == which.max(clu$csize)))
-  }
-
-  g <- giant.component(sample_gnp(100, 3 / 100))
-  md <- mean_distance(g, details = TRUE)
-  expect_equal(apl(g), md$res)
-
-  g <- make_full_graph(5) %du% make_full_graph(7)
-  md <- mean_distance(g, details = TRUE, unconnected = TRUE)
-  expect_equal(1, md$res)
-  expect_equal(70, md$unconnected)
-
-  g <- make_full_graph(5) %du% make_full_graph(7)
-  md <- mean_distance(g, details = TRUE, unconnected = FALSE)
-  expect_equal(Inf, md$res)
-  expect_equal(70, md$unconnected)
-})
diff --git a/tests/testthat/test-contract.vertices.R b/tests/testthat/test-contract.vertices.R
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/tests/testthat/test-count.multiple.R b/tests/testthat/test-count.multiple.R
deleted file mode 100644
index 8bec886d59e..00000000000
--- a/tests/testthat/test-count.multiple.R
+++ /dev/null
@@ -1,37 +0,0 @@
-test_that("any_multiple(), count_multiple(), which_multiple() works", {
-  # g <- sample_pa(10, m = 3, algorithm = "bag")
-  g <- graph_from_edgelist(cbind(
-    c(2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10),
-    c(1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 3, 4, 3, 1, 1, 1, 3, 1, 2, 4, 1, 1, 2, 4, 1, 4, 1)
-  ))
-  im <- which_multiple(g)
-  cm <- count_multiple(g)
-  expect_true(any_multiple(g))
-  expect_equal(im, c(FALSE, TRUE, TRUE, FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE))
-  expect_equal(cm, c(3, 3, 3, 3, 3, 3, 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2))
-  expect_equal(
-    count_multiple(simplify(g)),
-    rep(1, ecount(simplify(g)))
-  )
-
-
-  ## Direction of the edge is important
-  expect_false(any_multiple(make_graph(c(1, 2, 2, 1))))
-  expect_equal(which_multiple(make_graph(c(1, 2, 2, 1))), c(FALSE, FALSE))
-  expect_equal(
-    which_multiple(make_graph(c(1, 2, 2, 1), dir = FALSE)),
-    c(FALSE, TRUE)
-  )
-
-  ## Remove multiple edges but keep multiplicity
-  # g <- sample_pa(10, m = 3, algorithm = "bag")
-  g <- graph_from_edgelist(cbind(
-    c(2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10),
-    c(1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 4, 1, 1, 6, 4, 1, 5, 8)
-  ))
-  E(g)$weight <- 1
-  g <- simplify(g)
-  expect_false(any_multiple(g))
-  expect_false(any(which_multiple(g)))
-  expect_equal(E(g)$weight, c(3, 2, 1, 2, 1, 3, 2, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1))
-})
diff --git a/tests/testthat/test-dyad.census.R b/tests/testthat/test-dyad.census.R
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/tests/testthat/test-graph.density.R b/tests/testthat/test-graph.density.R
deleted file mode 100644
index ce7fb06436e..00000000000
--- a/tests/testthat/test-graph.density.R
+++ /dev/null
@@ -1,13 +0,0 @@
-test_that("edge_density works", {
-  g <- sample_gnp(50, 4 / 50)
-  gd <- edge_density(g)
-  gd2 <- ecount(g) / vcount(g) / (vcount(g) - 1) * 2
-  expect_equal(gd, gd2)
-
-  ####
-
-  g <- sample_gnp(50, 4 / 50, directed = TRUE)
-  gd <- edge_density(g)
-  gd2 <- ecount(g) / vcount(g) / (vcount(g) - 1)
-  expect_equal(gd, gd2)
-})
diff --git a/tests/testthat/test-graph.knn.R b/tests/testthat/test-graph.knn.R
deleted file mode 100644
index f91dfca1ae7..00000000000
--- a/tests/testthat/test-graph.knn.R
+++ /dev/null
@@ -1,31 +0,0 @@
-test_that("knn works", {
-  withr::local_seed(42)
-
-  ## Some trivial ones
-  g <- make_ring(10)
-  expect_equal(knn(g), list(knn = rep(2, 10), knnk = c(NaN, 2)))
-
-  g2 <- make_star(10)
-  expect_equal(knn(g2), list(knn = c(1, rep(9, 9)), knnk = c(9, rep(NaN, 7), 1)))
-
-  ## A scale-free one, try to plot 'knnk'
-  g3 <- simplify(sample_pa(1000, m = 5))
-  r3 <- knn(g3)
-  expect_equal(r3$knn[43], 46)
-  expect_equal(r3$knn[1000], 192.4)
-  expect_equal(r3$knnk[100], 18.78)
-  expect_equal(length(r3$knnk), 359)
-
-  ## A random graph
-  g4 <- sample_gnp(1000, p = 5 / 1000)
-  r4 <- knn(g4)
-  expect_equal(r4$knn[1000], 20 / 3)
-  expect_equal(length(r4$knnk), 15)
-  expect_equal(r4$knnk[12], 19 / 3)
-
-  ## A weighted graph
-  g5 <- make_star(10)
-  E(g5)$weight <- seq(ecount(g5))
-  r5 <- knn(g5)
-  expect_equal(r5, structure(list(knn = c(1, rep(9, 9)), knnk = c(9, NaN, NaN, NaN, NaN, NaN, NaN, NaN, 1)), .Names = c("knn", "knnk")))
-})
diff --git a/tests/testthat/test-reciprocity.R b/tests/testthat/test-reciprocity.R
deleted file mode 100644
index f15aecc746e..00000000000
--- a/tests/testthat/test-reciprocity.R
+++ /dev/null
@@ -1,5 +0,0 @@
-test_that("reciprocity works", {
-  g <- make_graph(c(1, 2, 2, 1, 2, 3, 3, 4, 4, 4), directed = TRUE)
-  expect_equal(reciprocity(g), 0.5)
-  expect_equal(reciprocity(g, ignore.loops = FALSE), 0.6)
-})
diff --git a/tests/testthat/test-structural.properties.R b/tests/testthat/test-structural.properties.R
index b6bfae6a708..6fef196856c 100644
--- a/tests/testthat/test-structural.properties.R
+++ b/tests/testthat/test-structural.properties.R
@@ -26,31 +26,32 @@ test_that("bfs() deprecated argument", {
 })
 
 test_that("degree() works", {
-  g <- sample_gnp(100, 1 / 100)
-  d <- degree(g)
-  el <- as_edgelist(g)
-  expect_equal(as.numeric(table(el)), d[d != 0])
+  gnp1 <- sample_gnp(100, 1 / 100)
+  gnp1_deg <- degree(gnp1)
+  el <- as_edgelist(gnp1)
+  expect_equal(as.numeric(table(el)), gnp1_deg[gnp1_deg != 0])
 
-  expect_equal(degree(g) / (vcount(g) - 1), degree(g, normalized = TRUE))
+  expect_equal(gnp1_deg / (vcount(gnp1) - 1), degree(gnp1, normalized = TRUE))
 
-  g2 <- sample_gnp(100, 2 / 100, directed = TRUE)
-  din <- degree(g2, mode = "in")
-  dout <- degree(g2, mode = "out")
-  el2 <- as_edgelist(g2)
-  expect_equal(as.numeric(table(el2[, 1])), dout[dout != 0])
-  expect_equal(as.numeric(table(el2[, 2])), din[din != 0])
+  gnp2 <- sample_gnp(100, 2 / 100, directed = TRUE)
+  gnp2_deg_in <- degree(gnp2, mode = "in")
+  el2 <- as_edgelist(gnp2)
+  expect_equal(as.numeric(table(el2[, 2])), gnp2_deg_in[gnp2_deg_in != 0])
+
+  gnp2_deg_out <- degree(gnp2, mode = "out")
+  expect_equal(as.numeric(table(el2[, 1])), gnp2_deg_out[gnp2_deg_out != 0])
 
   expect_equal(
-    degree(g2, mode = "in") / (vcount(g2) - 1),
-    degree(g2, mode = "in", normalized = TRUE)
+    gnp2_deg_in / (vcount(gnp2) - 1),
+    degree(gnp2, mode = "in", normalized = TRUE)
   )
   expect_equal(
-    degree(g2, mode = "out") / (vcount(g2) - 1),
-    degree(g2, mode = "out", normalized = TRUE)
+    gnp2_deg_out / (vcount(gnp2) - 1),
+    degree(gnp2, mode = "out", normalized = TRUE)
   )
   expect_equal(
-    degree(g2, mode = "all") / (vcount(g2) - 1),
-    degree(g2, mode = "all", normalized = TRUE)
+    degree(gnp2, mode = "all") / (vcount(gnp2) - 1),
+    degree(gnp2, mode = "all", normalized = TRUE)
   )
 })
 
@@ -94,7 +95,8 @@ test_that("BFS works from multiple root vertices", {
   )
 })
 
-test_that("issue 133", {
+test_that("BFS the restricted set is one indexed", {
+  # https://github.com/igraph/rigraph/issues/133
   g <- graph_from_edgelist(matrix(c(1, 2, 2, 3), ncol = 2, byrow = TRUE))
 
   expect_equal(
@@ -502,15 +504,16 @@ test_that("local transitivity() produces named vectors", {
   g <- make_graph(~ a - b - c - a - d)
   E(g)$weight <- 1:4
   t1 <- transitivity(g, type = "local")
+  expect_equal(names(t1), V(g)$name)
+
   t2 <- transitivity(g, type = "barrat")
+  expect_equal(names(t2), V(g)$name)
 
   vs <- c("a", "c")
   t3 <- transitivity(g, type = "local", vids = vs)
-  t4 <- transitivity(g, type = "barrat", vids = vs)
-
-  expect_equal(names(t1), V(g)$name)
-  expect_equal(names(t2), V(g)$name)
   expect_equal(names(t3), vs)
+
+  t4 <- transitivity(g, type = "barrat", vids = vs)
   expect_equal(names(t4), vs)
 })
 
@@ -729,3 +732,163 @@ test_that("coreness() works", {
   gc <- coreness(g)
   expect_equal(gc, c(3, 3, 3, 2, 2, 2, 2, 2, 2, 2))
 })
+
+test_that("mean_distance works", {
+  avg_path_length <- function(graph) {
+    sp <- distances(graph, mode = "out")
+    if (is_directed(graph)) {
+      diag(sp) <- NA
+    } else {
+      sp[lower.tri(sp, diag = TRUE)] <- NA
+    }
+    sp[sp == "Inf"] <- NA
+    mean(sp, na.rm = TRUE)
+  }
+
+  giant.component <- function(graph, mode = "weak") {
+    clu <- components(graph, mode = mode)
+    induced_subgraph(graph, which(clu$membership == which.max(clu$csize)))
+  }
+
+  g <- giant.component(sample_gnp(100, 3 / 100))
+  expect_equal(avg_path_length(g), mean_distance(g))
+
+  g <- giant.component(sample_gnp(100, 6 / 100, directed = TRUE), mode = "strong")
+  expect_equal(avg_path_length(g), mean_distance(g))
+
+  g <- sample_gnp(100, 2 / 100)
+  expect_equal(avg_path_length(g), mean_distance(g))
+
+  g <- sample_gnp(100, 4 / 100, directed = TRUE)
+  expect_equal(avg_path_length(g), mean_distance(g))
+})
+
+test_that("mean_distance works correctly for disconnected graphs", {
+  g <- make_full_graph(5) %du% make_full_graph(7)
+  md <- mean_distance(g, unconnected = FALSE)
+  expect_equal(Inf, md)
+  md <- mean_distance(g, unconnected = TRUE)
+  expect_equal(1, md)
+})
+
+test_that("mean_distance can provide details", {
+  avg_path_length <- function(graph) {
+    sp <- distances(graph, mode = "out")
+    if (is_directed(graph)) {
+      diag(sp) <- NA
+    } else {
+      sp[lower.tri(sp, diag = TRUE)] <- NA
+    }
+    sp[sp == "Inf"] <- NA
+    mean(sp, na.rm = TRUE)
+  }
+
+  giant.component <- function(graph, mode = "weak") {
+    clu <- components(graph, mode = mode)
+    induced_subgraph(graph, which(clu$membership == which.max(clu$csize)))
+  }
+
+  g <- giant.component(sample_gnp(100, 3 / 100))
+  md <- mean_distance(g, details = TRUE)
+  expect_equal(avg_path_length(g), md$res)
+
+  g <- make_full_graph(5) %du% make_full_graph(7)
+  md <- mean_distance(g, details = TRUE, unconnected = TRUE)
+  expect_equal(1, md$res)
+  expect_equal(70, md$unconnected)
+
+  g <- make_full_graph(5) %du% make_full_graph(7)
+  md <- mean_distance(g, details = TRUE, unconnected = FALSE)
+  expect_equal(Inf, md$res)
+  expect_equal(70, md$unconnected)
+})
+
+test_that("any_multiple(), count_multiple(), which_multiple() works", {
+  # g <- sample_pa(10, m = 3, algorithm = "bag")
+  g <- graph_from_edgelist(cbind(
+    c(2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10),
+    c(1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 3, 4, 3, 1, 1, 1, 3, 1, 2, 4, 1, 1, 2, 4, 1, 4, 1)
+  ))
+  im <- which_multiple(g)
+  cm <- count_multiple(g)
+  expect_true(any_multiple(g))
+  expect_equal(im, c(FALSE, TRUE, TRUE, FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE))
+  expect_equal(cm, c(3, 3, 3, 3, 3, 3, 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2))
+  expect_equal(
+    count_multiple(simplify(g)),
+    rep(1, ecount(simplify(g)))
+  )
+
+
+  ## Direction of the edge is important
+  expect_false(any_multiple(make_graph(c(1, 2, 2, 1))))
+  expect_equal(which_multiple(make_graph(c(1, 2, 2, 1))), c(FALSE, FALSE))
+  expect_equal(
+    which_multiple(make_graph(c(1, 2, 2, 1), dir = FALSE)),
+    c(FALSE, TRUE)
+  )
+
+  ## Remove multiple edges but keep multiplicity
+  # g <- sample_pa(10, m = 3, algorithm = "bag")
+  g <- graph_from_edgelist(cbind(
+    c(2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10),
+    c(1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 4, 1, 1, 6, 4, 1, 5, 8)
+  ))
+  E(g)$weight <- 1
+  g <- simplify(g)
+  expect_false(any_multiple(g))
+  expect_false(any(which_multiple(g)))
+  expect_equal(E(g)$weight, c(3, 2, 1, 2, 1, 3, 2, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1))
+})
+
+test_that("edge_density works", {
+  g <- sample_gnp(50, 4 / 50)
+  gd <- edge_density(g)
+  gd2 <- ecount(g) / vcount(g) / (vcount(g) - 1) * 2
+  expect_equal(gd, gd2)
+
+  ####
+
+  g <- sample_gnp(50, 4 / 50, directed = TRUE)
+  gd <- edge_density(g)
+  gd2 <- ecount(g) / vcount(g) / (vcount(g) - 1)
+  expect_equal(gd, gd2)
+})
+
+test_that("knn works", {
+  withr::local_seed(42)
+
+  ## Some trivial ones
+  g <- make_ring(10)
+  expect_equal(knn(g), list(knn = rep(2, 10), knnk = c(NaN, 2)))
+
+  g2 <- make_star(10)
+  expect_equal(knn(g2), list(knn = c(1, rep(9, 9)), knnk = c(9, rep(NaN, 7), 1)))
+
+  ## A scale-free one, try to plot 'knnk'
+  g3 <- simplify(sample_pa(1000, m = 5))
+  r3 <- knn(g3)
+  expect_equal(r3$knn[43], 46)
+  expect_equal(r3$knn[1000], 192.4)
+  expect_equal(r3$knnk[100], 18.78)
+  expect_equal(length(r3$knnk), 359)
+
+  ## A random graph
+  g4 <- sample_gnp(1000, p = 5 / 1000)
+  r4 <- knn(g4)
+  expect_equal(r4$knn[1000], 20 / 3)
+  expect_equal(length(r4$knnk), 15)
+  expect_equal(r4$knnk[12], 19 / 3)
+
+  ## A weighted graph
+  g5 <- make_star(10)
+  E(g5)$weight <- seq(ecount(g5))
+  r5 <- knn(g5)
+  expect_equal(r5, structure(list(knn = c(1, rep(9, 9)), knnk = c(9, NaN, NaN, NaN, NaN, NaN, NaN, NaN, 1)), .Names = c("knn", "knnk")))
+})
+
+test_that("reciprocity works", {
+  g <- make_graph(c(1, 2, 2, 1, 2, 3, 3, 4, 4, 4), directed = TRUE)
+  expect_equal(reciprocity(g), 0.5)
+  expect_equal(reciprocity(g, ignore.loops = FALSE), 0.6)
+})