diff --git a/test/functions.ts b/test/functions.ts
new file mode 100644
index 0000000..fa9aaf7
--- /dev/null
+++ b/test/functions.ts
@@ -0,0 +1,95 @@
+import test from "ava"
+
+import { get_nextflow_release } from "../src/functions"
+import { NextflowRelease } from "../src/nextflow-release"
+
+// The Nextflow releases we are going to use for testing follow a regular
+// pattern: create a mock function to bootstrap some test data without repeating
+// ourselves
+function nf_release_gen(version_number: string): NextflowRelease {
+  const is_edge = version_number.endsWith("-edge")
+  const release: NextflowRelease = {
+    version: version_number,
+    isEdge: is_edge,
+    downloadUrl: `https://github.com/nextflow-io/nextflow/releases/download/${version_number}/nextflow`,
+    downloadUrlAll: `https://github.com/nextflow-io/nextflow/releases/download/${version_number}/nextflow-${version_number.replace(
+      "v",
+      ""
+    )}-all`
+  }
+  return release
+}
+
+const release_test_macro = test.macro(
+  async (
+    t,
+    input_version: string,
+    expected_version: string,
+    is_edge_older: Boolean
+  ) => {
+    const releases_set = [
+      nf_release_gen("v21.05.1-edge"),
+      nf_release_gen("v21.05.0-edge"),
+      nf_release_gen("v21.04.2"),
+      nf_release_gen("v21.04.1"),
+      nf_release_gen("v21.04.0"),
+      nf_release_gen("v21.03.0-edge")
+    ]
+    const release_filtered = releases_set.splice(is_edge_older ? 2 : 0)
+    const matched_release = await get_nextflow_release(
+      input_version,
+      release_filtered
+    )
+    t.is(matched_release.version, expected_version)
+  }
+)
+
+test(
+  "Major and minor version only (edge newer)",
+  release_test_macro,
+  "v21.04",
+  "v21.04.2",
+  false
+)
+test(
+  "Major and minor version only (edge older)",
+  release_test_macro,
+  "v21.04",
+  "v21.04.2",
+  true
+)
+test(
+  "Major, minor, and patch version: latest patch (edge newer)",
+  release_test_macro,
+  "v21.04.2",
+  "v21.04.2",
+  false
+)
+test(
+  "Major, minor, and patch version: latest patch (edge older)",
+  release_test_macro,
+  "v21.04.2",
+  "v21.04.2",
+  true
+)
+test(
+  "Major, minor, and patch version: older patch (edge newer)",
+  release_test_macro,
+  "v21.04.1",
+  "v21.04.1",
+  false
+)
+test(
+  "Major, minor, and patch version: older patch (edge older)",
+  release_test_macro,
+  "v21.04.1",
+  "v21.04.1",
+  true
+)
+test(
+  "Edge release",
+  release_test_macro,
+  "v21.03.0-edge",
+  "v21.03.0-edge",
+  false
+)