diff --git a/tests/testthat/test-get_clustered_median_exon_expression.R b/tests/testthat/test-get_clustered_median_exon_expression.R
new file mode 100644
index 0000000..22392ed
--- /dev/null
+++ b/tests/testthat/test-get_clustered_median_exon_expression.R
@@ -0,0 +1,22 @@
+test_that("`get_clustered_median_exon_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_clustered_median_exon_expression(c("ENSG00000203782.5", "ENSG00000132693.12"),
+                                                           tissueSiteDetailIds = "Bladder")
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "exonId",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_clustered_median_gene_expression.R b/tests/testthat/test-get_clustered_median_gene_expression.R
new file mode 100644
index 0000000..f0e10e2
--- /dev/null
+++ b/tests/testthat/test-get_clustered_median_gene_expression.R
@@ -0,0 +1,21 @@
+test_that("`get_clustered_median_gene_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_clustered_median_gene_expression(c("ENSG00000203782.5", "ENSG00000132693.12"),
+                                                           tissueSiteDetailIds = "Bladder")
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_clustered_median_junction_expression.R b/tests/testthat/test-get_clustered_median_junction_expression.R
new file mode 100644
index 0000000..61a64bc
--- /dev/null
+++ b/tests/testthat/test-get_clustered_median_junction_expression.R
@@ -0,0 +1,24 @@
+test_that(
+  "`get_clustered_median_junction_expression()` returns tibble with expected colnames",
+  {
+    skip_if_offline()
+    result <- get_clustered_median_junction_expression(c("ENSG00000203782.5", "ENSG00000132693.12"),
+                                                       tissueSiteDetailIds = "Bladder")
+
+    expect_s3_class(result, "tbl_df")
+
+    expect_identical(
+      names(result),
+      c(
+        "median",
+        "junctionId",
+        "tissueSiteDetailId",
+        "ontologyId",
+        "datasetId",
+        "gencodeId",
+        "geneSymbol",
+        "unit"
+      )
+    )
+  }
+)
diff --git a/tests/testthat/test-get_clustered_median_transcript_expression.R b/tests/testthat/test-get_clustered_median_transcript_expression.R
new file mode 100644
index 0000000..d87e32c
--- /dev/null
+++ b/tests/testthat/test-get_clustered_median_transcript_expression.R
@@ -0,0 +1,24 @@
+test_that(
+  "`get_clustered_median_transcript_expression()` returns tibble with expected colnames",
+  {
+    skip_if_offline()
+    result <- get_clustered_median_transcript_expression(c("ENSG00000203782.5", "ENSG00000132693.12"),
+                                                         tissueSiteDetailIds = "Bladder")
+
+    expect_s3_class(result, "tbl_df")
+
+    expect_identical(
+      names(result),
+      c(
+        "median",
+        "transcriptId",
+        "tissueSiteDetailId",
+        "ontologyId",
+        "datasetId",
+        "gencodeId",
+        "geneSymbol",
+        "unit"
+      )
+    )
+  }
+)
diff --git a/tests/testthat/test-get_expression_pca.R b/tests/testthat/test-get_expression_pca.R
new file mode 100644
index 0000000..d7a0947
--- /dev/null
+++ b/tests/testthat/test-get_expression_pca.R
@@ -0,0 +1,20 @@
+test_that("`get_expression_pca()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_expression_pca(tissueSiteDetailIds = "Adipose_Subcutaneous", sampleId = "GTEX-1117F-0226-SM-5GZZ7")
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "pc1",
+                "pc2",
+                "pc3",
+                "sampleId",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_gene_expression.R b/tests/testthat/test-get_gene_expression.R
new file mode 100644
index 0000000..f6ed375
--- /dev/null
+++ b/tests/testthat/test-get_gene_expression.R
@@ -0,0 +1,21 @@
+test_that("`get_gene_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_gene_expression(gencodeIds = "ENSG00000132693.12", tissueSiteDetailIds = "Whole_Blood")
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "data",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit",
+                "subsetGroup"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_median_exon_expression.R b/tests/testthat/test-get_median_exon_expression.R
new file mode 100644
index 0000000..29c1872
--- /dev/null
+++ b/tests/testthat/test-get_median_exon_expression.R
@@ -0,0 +1,21 @@
+test_that("`get_median_exon_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_median_exon_expression(gencodeIds = "ENSG00000132693.12", tissueSiteDetailIds = "Whole_Blood")
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "exonId",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_median_gene_expression.R b/tests/testthat/test-get_median_gene_expression.R
new file mode 100644
index 0000000..a4fe407
--- /dev/null
+++ b/tests/testthat/test-get_median_gene_expression.R
@@ -0,0 +1,21 @@
+test_that("`get_median_gene_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_median_gene_expression(gencodeIds = "ENSG00000132693.12", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_median_junction_expression.R b/tests/testthat/test-get_median_junction_expression.R
new file mode 100644
index 0000000..a6a905c
--- /dev/null
+++ b/tests/testthat/test-get_median_junction_expression.R
@@ -0,0 +1,22 @@
+test_that("`get_median_junction_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_median_junction_expression(gencodeIds = "ENSG00000132693.12", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "junctionId",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_median_transcript_expression.R b/tests/testthat/test-get_median_transcript_expression.R
new file mode 100644
index 0000000..b938184
--- /dev/null
+++ b/tests/testthat/test-get_median_transcript_expression.R
@@ -0,0 +1,22 @@
+test_that("`get_median_transcript_expression()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_median_transcript_expression(gencodeIds = "ENSG00000132693.12", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "median",
+                "transcriptId",
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_single_nucleus_gex.R b/tests/testthat/test-get_single_nucleus_gex.R
new file mode 100644
index 0000000..ec1a247
--- /dev/null
+++ b/tests/testthat/test-get_single_nucleus_gex.R
@@ -0,0 +1,21 @@
+test_that("`get_single_nucleus_gex()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_single_nucleus_gex(gencodeIds = "ENSG00000132693.12", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "cellTypes",
+                "unit"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_single_nucleus_gex_summary.R b/tests/testthat/test-get_single_nucleus_gex_summary.R
new file mode 100644
index 0000000..177e24f
--- /dev/null
+++ b/tests/testthat/test-get_single_nucleus_gex_summary.R
@@ -0,0 +1,19 @@
+test_that("`get_single_nucleus_gex_summary()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_single_nucleus_gex_summary(tissueSiteDetailIds = "Breast_Mammary_Tissue", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "cellType",
+                "numCells"
+              )
+            )
+          })
diff --git a/tests/testthat/test-get_top_expressed_genes.R b/tests/testthat/test-get_top_expressed_genes.R
new file mode 100644
index 0000000..ee043c6
--- /dev/null
+++ b/tests/testthat/test-get_top_expressed_genes.R
@@ -0,0 +1,21 @@
+test_that("`get_top_expressed_genes()` returns tibble with expected colnames",
+          {
+            skip_if_offline()
+            result <- get_top_expressed_genes(tissueSiteDetailId = "Breast_Mammary_Tissue", itemsPerPage = 1) |>
+              suppressWarnings()
+
+            expect_s3_class(result, "tbl_df")
+
+            expect_identical(
+              names(result),
+              c(
+                "tissueSiteDetailId",
+                "ontologyId",
+                "datasetId",
+                "gencodeId",
+                "geneSymbol",
+                "median",
+                "unit"
+              )
+            )
+          })