diff --git a/NAMESPACE b/NAMESPACE
index 4677547..4f63b48 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -15,6 +15,7 @@ S3method(arrange,GInteractions)
 S3method(as_ginteractions,data.frame)
 S3method(as_ginteractions,default)
 S3method(count,GInteractions)
+S3method(count,GroupedGInteractions)
 S3method(count_overlaps,GInteractions)
 S3method(count_overlaps,PinnedGInteractions)
 S3method(count_overlaps_directed,GInteractions)
diff --git a/tests/testthat/test-classes.R b/tests/testthat/test-classes.R
index ab0226f..c919b88 100644
--- a/tests/testthat/test-classes.R
+++ b/tests/testthat/test-classes.R
@@ -204,4 +204,150 @@ test_that("classes work", {
     gi |> ungroup() |> expect_error("GInteractions")
     show(ggi) |> expect_no_error()
 
+    ## DelegatingGInteractions
+    expect_identical(
+        anchors1(apgi), 
+        new("GRanges", seqnames = new("Rle", values = structure(1L, levels = c("chr1", 
+        "chr2"), class = "factor"), lengths = 4L, elementMetadata = NULL, 
+            metadata = list()), ranges = new("IRanges", start = c(11L, 
+        11L, 11L, 11L), width = c(10L, 10L, 20L, 20L), NAMES = NULL, 
+            elementType = "ANY", elementMetadata = NULL, metadata = list()), 
+            strand = new("Rle", values = structure(1:2, levels = c("+", 
+            "-", "*"), class = "factor"), lengths = c(2L, 2L), elementMetadata = NULL, 
+                metadata = list()), seqinfo = new("Seqinfo", seqnames = c("chr1", 
+            "chr2"), seqlengths = c(NA_integer_, NA_integer_), is_circular = c(NA, 
+            NA), genome = c(NA_character_, NA_character_)), elementMetadata = new("DFrame", 
+                rownames = NULL, nrows = 4L, elementType = "ANY", elementMetadata = NULL, 
+                metadata = list(), listData = structure(list(), names = character(0))), 
+            elementType = "ANY", metadata = list())
+    )
+    expect_identical(
+        ranges1(apgi), 
+        new("IRanges", start = c(11L, 11L, 11L, 11L), width = c(10L, 
+        10L, 20L, 20L), NAMES = NULL, elementType = "ANY", elementMetadata = NULL, 
+            metadata = list())
+    )
+    expect_identical(
+        seqnames1(apgi), 
+        new("Rle", values = structure(1L, levels = c("chr1", "chr2"), class = "factor"), 
+        lengths = 4L, elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        start1(apgi), 
+        c(11L, 11L, 11L, 11L)
+    )
+    expect_identical(
+        end1(apgi), 
+        c(20L, 20L, 30L, 30L)
+    )
+    expect_identical(
+        width1(apgi), 
+        c(10L, 10L, 20L, 20L)
+    )
+    expect_identical(
+        strand1(apgi), 
+        new("Rle", values = structure(1:2, levels = c("+", "-", "*"), class = "factor"), 
+        lengths = c(2L, 2L), elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        anchors2(apgi), 
+        new("GRanges", seqnames = new("Rle", values = structure(1:2, levels = c("chr1", 
+        "chr2"), class = "factor"), lengths = c(3L, 1L), elementMetadata = NULL, 
+            metadata = list()), ranges = new("IRanges", start = c(21L, 
+        51L, 51L, 51L), width = c(10L, 5L, 5L, 10L), NAMES = NULL, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list()), strand = new("Rle", 
+            values = structure(1:2, levels = c("+", "-", "*"), class = "factor"), 
+            lengths = c(2L, 2L), elementMetadata = NULL, metadata = list()), 
+            seqinfo = new("Seqinfo", seqnames = c("chr1", "chr2"), seqlengths = c(NA_integer_, 
+            NA_integer_), is_circular = c(NA, NA), genome = c(NA_character_, 
+            NA_character_)), elementMetadata = new("DFrame", rownames = NULL, 
+                nrows = 4L, elementType = "ANY", elementMetadata = NULL, 
+                metadata = list(), listData = structure(list(), names = character(0))), 
+            elementType = "ANY", metadata = list())
+    )
+    expect_identical(
+        ranges2(apgi), 
+        new("IRanges", start = c(21L, 51L, 51L, 51L), width = c(10L, 
+        5L, 5L, 10L), NAMES = NULL, elementType = "ANY", elementMetadata = NULL, 
+            metadata = list())
+    )
+    expect_identical(
+        seqnames2(apgi), 
+        new("Rle", values = structure(1:2, levels = c("chr1", "chr2"), class = "factor"), 
+            lengths = c(3L, 1L), elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        start2(apgi), 
+        c(21L, 51L, 51L, 51L)
+    )
+    expect_identical(
+        end2(apgi), 
+        c(30L, 55L, 55L, 60L)
+    )
+    expect_identical(
+        width2(apgi), 
+        c(10L, 5L, 5L, 10L)
+    )
+    expect_identical(
+        strand2(apgi), 
+        new("Rle", values = structure(1:2, levels = c("+", "-", "*"), class = "factor"), 
+            lengths = c(2L, 2L), elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        anchors(apgi), 
+        list(first = new("GRanges", seqnames = new("Rle", values = structure(1L, levels = c("chr1", 
+        "chr2"), class = "factor"), lengths = 4L, elementMetadata = NULL, 
+            metadata = list()), ranges = new("IRanges", start = c(11L, 
+        11L, 11L, 11L), width = c(10L, 10L, 20L, 20L), NAMES = NULL, 
+            elementType = "ANY", elementMetadata = NULL, metadata = list()), 
+            strand = new("Rle", values = structure(1:2, levels = c("+", 
+            "-", "*"), class = "factor"), lengths = c(2L, 2L), elementMetadata = NULL, 
+                metadata = list()), seqinfo = new("Seqinfo", seqnames = c("chr1", 
+            "chr2"), seqlengths = c(NA_integer_, NA_integer_), is_circular = c(NA, 
+            NA), genome = c(NA_character_, NA_character_)), elementMetadata = new("DFrame", 
+                rownames = NULL, nrows = 4L, elementType = "ANY", elementMetadata = NULL, 
+                metadata = list(), listData = structure(list(), names = character(0))), 
+            elementType = "ANY", metadata = list()), second = new("GRanges", 
+            seqnames = new("Rle", values = structure(1:2, levels = c("chr1", 
+            "chr2"), class = "factor"), lengths = c(3L, 1L), elementMetadata = NULL, 
+                metadata = list()), ranges = new("IRanges", start = c(21L, 
+            51L, 51L, 51L), width = c(10L, 5L, 5L, 10L), NAMES = NULL, 
+                elementType = "ANY", elementMetadata = NULL, metadata = list()), 
+            strand = new("Rle", values = structure(1:2, levels = c("+", 
+            "-", "*"), class = "factor"), lengths = c(2L, 2L), elementMetadata = NULL, 
+                metadata = list()), seqinfo = new("Seqinfo", seqnames = c("chr1", 
+            "chr2"), seqlengths = c(NA_integer_, NA_integer_), is_circular = c(NA, 
+            NA), genome = c(NA_character_, NA_character_)), elementMetadata = new("DFrame", 
+                rownames = NULL, nrows = 4L, elementType = "ANY", elementMetadata = NULL, 
+                metadata = list(), listData = structure(list(), names = character(0))), 
+            elementType = "ANY", metadata = list()))
+    )
+    expect_identical(
+        regions(apgi), 
+        new("GRanges", seqnames = new("Rle", values = structure(1:2, levels = c("chr1", 
+        "chr2"), class = "factor"), lengths = c(5L, 1L), elementMetadata = NULL, 
+            metadata = list()), ranges = new("IRanges", start = c(11L, 
+        21L, 51L, 11L, 51L, 51L), width = c(10L, 10L, 5L, 20L, 5L, 10L
+        ), NAMES = NULL, elementType = "ANY", elementMetadata = NULL, 
+            metadata = list()), strand = new("Rle", values = structure(1:2, levels = c("+", 
+        "-", "*"), class = "factor"), lengths = c(3L, 3L), elementMetadata = NULL, 
+            metadata = list()), seqinfo = new("Seqinfo", seqnames = c("chr1", 
+        "chr2"), seqlengths = c(NA_integer_, NA_integer_), is_circular = c(NA, 
+        NA), genome = c(NA_character_, NA_character_)), elementMetadata = new("DFrame", 
+            rownames = NULL, nrows = 6L, elementType = "ANY", elementMetadata = NULL, 
+            metadata = list(), listData = structure(list(), names = character(0))), 
+            elementType = "ANY", metadata = list())
+    )
+    expect_identical(
+        seqinfo(apgi), 
+        new("Seqinfo", seqnames = c("chr1", "chr2"), seqlengths = c(NA_integer_, 
+        NA_integer_), is_circular = c(NA, NA), genome = c(NA_character_, 
+        NA_character_))
+    )
+    expect_identical(
+        mcols(apgi)[,2], 
+        c("cis", "cis", "cis", "trans")
+    )
+    show(apgi) |> expect_no_error()
+
 })
diff --git a/tests/testthat/test-dplyr.R b/tests/testthat/test-dplyr.R
index c0e2473..3559d19 100644
--- a/tests/testthat/test-dplyr.R
+++ b/tests/testthat/test-dplyr.R
@@ -12,19 +12,110 @@ test_that("dplyr functions work", {
     ## tally/count
 
     ggi |> count(strand1) |> expect_no_error()
-    ggi |> tally() |> expect_no_error()
-    gi |> count(strand1) |> expect_s4_class("DataFrame")
-    gi |> tally() |> expect_error()
+    expect_identical(
+        ggi |> count(group), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), n = c(2L, 2L)))
+    )
+    expect_identical(
+        ggi |> count(type), 
+        new("DFrame", rownames = NULL, nrows = 3L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2, 2), type = c("cis", "cis", "trans"), 
+                n = c(2L, 1L, 1L)))
+    )
+    expect_identical(
+        ggi |> tally(), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), n = c(2L, 2L)))
+    )
+    expect_identical(
+        ggi |> count(strand1), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), strand1 = new("Rle", values = structure(1:2, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(2L, 2L)))
+    )
+    expect_identical(
+        gi |> count(strand1), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                strand1 = new("Rle", values = structure(1:2, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(2L, 2L)))
+    )
+    expect_identical(
+        ggi |> count(strand1, wt = score), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), strand1 = new("Rle", values = structure(1:2, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(0.736002816120163, 1.23265417455696
+                ))), 
+        tolerance = 1e-4
+    )
+    expect_identical(
+        gi |> count(strand1, wt = score), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                strand1 = new("Rle", values = structure(1:2, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(0.736002816120163, 1.23265417455696
+                ))), 
+        tolerance = 1e-4
+    )
+    expect_identical(
+        ggi |> count(strand1, wt = score, sort = TRUE), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(2, 1), strand1 = new("Rle", values = structure(2:1, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(1.23265417455696, 0.736002816120163
+                ))), 
+        tolerance = 1e-4
+    )
+    expect_identical(
+        gi |> count(strand1, wt = score, sort = TRUE), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                strand1 = new("Rle", values = structure(2:1, levels = c("+", 
+                "-", "*"), class = "factor"), lengths = c(1L, 1L), elementMetadata = NULL, 
+                    metadata = list()), n = c(1.23265417455696, 0.736002816120163
+                ))), 
+        tolerance = 1e-4
+    )
 
     ## filter
 
-    expect_identical(gi |> filter(strand1 == '-') |> length(), 2L)
+    expect_identical(
+        gi |> filter(strand1 == '-') |> ranges1(), 
+        new("IRanges", start = c(11L, 11L), width = c(20L, 20L), NAMES = NULL, 
+            elementType = "ANY", elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        gi |> filter(strand1 == '+') |> ranges1(), 
+        new("IRanges", start = c(11L, 11L), width = c(10L, 10L), NAMES = NULL, 
+            elementType = "ANY", elementMetadata = NULL, metadata = list())
+    )
     ggi |> filter(strand1 == '+') |> expect_error()
 
     ## mutate
 
-    gi |> mutate(strand1 = '-') |> expect_s4_class("GInteractions")
-    gi |> mutate(xxx = 1) |> expect_s4_class("GInteractions")
+    expect_identical(
+        gi |> mutate(strand1 = '-') |> strand1(), 
+        new("Rle", values = structure(2L, levels = c("+", "-", "*"), class = "factor"), 
+        lengths = 4L, elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        gi |> mutate(xxx = 1) |> mcols() |> subset(, c(2, 3)), 
+        new("DFrame", rownames = NULL, nrows = 4L, elementType = "ANY", 
+        elementMetadata = NULL, metadata = list(), listData = list(
+            type = c("cis", "cis", "cis", "trans"), xxx = c(1, 1, 
+            1, 1)))
+    )
     expect_identical(
         mutate(gi, xxx = IRanges::RleList(c(1, 2), c(3, 4)))$xxx,
         IRanges::RleList(c(1, 2), c(3, 4), c(1, 2), c(3, 4))
@@ -58,24 +149,87 @@ test_that("dplyr functions work", {
     )
 
     ## slice
-    gi |> slice(1:3) |> expect_s4_class("GInteractions")
+    expect_identical(
+        gi |> slice(1:3) |> start1(), 
+        c(11L, 11L, 11L)
+    )
     gi |> slice(1:5) |> expect_error()
     gi |> slice('error') |> expect_error()
 
     ## summarize
-    ggi |> summarize(m = mean(score))
-    ggi |> summarise(m = mean(score))
+    expect_identical(
+        ggi |> summarize(m = mean(score)), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+        elementMetadata = NULL, metadata = list(), listData = list(
+            group = c(1, 2), m = c(0.368001408060081, 0.616327087278478
+            ))), 
+        tolerance = 1e-4
+    )
+    expect_identical(
+        ggi |> summarize(m = table(type)), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), m = new("CompressedIntegerList", elementType = "integer", 
+                    elementMetadata = NULL, metadata = list(), unlistData = c(cis = 2L, 
+                    trans = 0L, cis = 1L, trans = 1L), partitioning = new("PartitioningByEnd", 
+                        end = c(2L, 4L), NAMES = c("1", "2"), elementType = "ANY", 
+                        elementMetadata = NULL, metadata = list()))))
+    )
+    expect_identical(
+        ggi |> summarize(m = table(type), n = table(group)), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2), m = new("CompressedIntegerList", elementType = "integer", 
+                    elementMetadata = NULL, metadata = list(), unlistData = c(cis = 2L, 
+                    trans = 0L, cis = 1L, trans = 1L), partitioning = new("PartitioningByEnd", 
+                        end = c(2L, 4L), NAMES = c("1", "2"), elementType = "ANY", 
+                        elementMetadata = NULL, metadata = list())), 
+                n = new("CompressedIntegerList", elementType = "integer", 
+                    elementMetadata = NULL, metadata = list(), unlistData = c(`1` = 2L, 
+                    `2` = 0L, `1` = 0L, `2` = 2L), partitioning = new("PartitioningByEnd", 
+                        end = c(2L, 4L), NAMES = c("1", "2"), elementType = "ANY", 
+                        elementMetadata = NULL, metadata = list()))))
+    )
 
 })
 
 test_that("dplyr group functions work", {
 
-    group_data(ggi) |> expect_s4_class("DataFrame")
-    group_keys(ggi) |> expect_s4_class("DataFrame")
-    expect_identical(group_indices(ggi), S4Vectors::Rle(c(1L, 1L, 2L, 2L)))
-    expect_identical(group_vars(ggi), "group")
-    expect_identical(groups(ggi), list(rlang::sym("group")))
-    expect_identical(group_size(ggi), c(2L, 2L))
-    expect_identical(n_groups(ggi), 2L)
+    expect_identical(
+        group_data(ggi), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+        elementMetadata = NULL, metadata = list(), listData = list(
+            group = c(1, 2), .rows = new("CompressedIntegerList", 
+                elementType = "integer", elementMetadata = NULL, 
+                metadata = list(), unlistData = 1:4, partitioning = new("PartitioningByEnd", 
+                    end = c(2L, 4L), NAMES = NULL, elementType = "ANY", 
+                    elementMetadata = NULL, metadata = list()))))
+    )
+    expect_identical(
+        group_keys(ggi), 
+        new("DFrame", rownames = NULL, nrows = 2L, elementType = "ANY", 
+            elementMetadata = NULL, metadata = list(), listData = list(
+                group = c(1, 2)))
+    )
+    expect_identical(
+        group_indices(ggi), 
+        S4Vectors::Rle(c(1L, 1L, 2L, 2L))
+    )
+    expect_identical(
+        group_vars(ggi), 
+        "group"
+    )
+    expect_identical(
+        groups(ggi), 
+        list(rlang::sym("group"))
+    )
+    expect_identical(
+        group_size(ggi), 
+        c(2L, 2L)
+    )
+    expect_identical(
+        n_groups(ggi), 
+        2L
+    )
 
 })
diff --git a/tests/testthat/test-setters.R b/tests/testthat/test-setters.R
index c8e6d6c..05766a4 100644
--- a/tests/testthat/test-setters.R
+++ b/tests/testthat/test-setters.R
@@ -1,14 +1,49 @@
 test_that("setter functions work", {
     
-    set_seqnames1(gi, factor("chr2", c("chr1", "chr2"))) |> expect_no_error()
-    set_seqnames2(gi, factor("chr2", c("chr1", "chr2"))) |> expect_no_error()
-    set_start1(gi, 1) |> expect_no_error()
-    set_start2(gi, 2) |> expect_no_error()
-    set_end1(gi, 100) |> expect_no_error()
-    set_end2(gi, 100) |> expect_no_error()
-    set_width1(gi, 10) |> expect_no_error()
-    set_width2(gi, 10) |> expect_no_error()
-    set_strand1(gi, '*') |> expect_no_error()
-    set_strand2(gi, c('-', '+', '-', '*')) |> expect_no_error()
+    expect_identical(
+        set_seqnames1(gi, factor("chr2", c("chr1", "chr2"))) |> seqnames1(), 
+        new("Rle", values = structure(2L, levels = c("chr1", "chr2"), class = "factor"), 
+            lengths = 4L, elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        set_seqnames2(gi, factor("chr2", c("chr1", "chr2"))) |> seqnames2(), 
+        new("Rle", values = structure(2L, levels = c("chr1", "chr2"), class = "factor"), 
+            lengths = 4L, elementMetadata = NULL, metadata = list())
+    )
+    expect_identical(
+        set_start1(gi, 1) |> start1(), 
+        c(1L, 1L, 1L, 1L)
+    )
+    expect_identical(
+        set_start2(gi, 2) |> start2(), 
+        c(2L, 2L, 2L, 2L)
+    )
+    expect_identical(
+        set_end1(gi, 10) |> end1(), 
+        c(10L, 10L, 10L, 10L)
+    )
+    expect_identical(
+        set_end2(gi, 200) |> end2(), 
+        c(200L, 200L, 200L, 200L)
+    )
+    expect_identical(
+        set_width1(gi, 10) |> width1(), 
+        c(10L, 10L, 10L, 10L)
+    )
+    expect_identical(
+        set_width2(gi, 200) |> width2(), 
+        c(200L, 200L, 200L, 200L)
+    )
+    expect_identical(
+        set_strand1(gi, c('-', '+', '-', '*')) |> strand1(), 
+        new("Rle", values = structure(c(2L, 1L, 2L, 3L), levels = c("+", 
+        "-", "*"), class = "factor"), lengths = c(1L, 1L, 1L, 1L), elementMetadata = NULL, 
+            metadata = list())
+    )
+    expect_identical(
+        set_strand2(gi, "*") |> strand2(), 
+        new("Rle", values = structure(3L, levels = c("+", "-", "*"), class = "factor"), 
+            lengths = 4L, elementMetadata = NULL, metadata = list())
+    )
 
 })