From d3cec0e99af7c4543ed2fc5a0843fa4bf309dcce Mon Sep 17 00:00:00 2001
From: Simon Li <spli@dundee.ac.uk>
Date: Wed, 10 Feb 2021 15:58:18 +0000
Subject: [PATCH] Handle empty ref

---
 __tests__/main.test.js | 7 ++++++-
 src/index.js           | 8 ++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/__tests__/main.test.js b/__tests__/main.test.js
index 1943626..4b46154 100644
--- a/__tests__/main.test.js
+++ b/__tests__/main.test.js
@@ -136,7 +136,7 @@ test("Unsupported prerelease tag", async () => {
 test("Not a tag", async () => {
   await expect(
     calculateTags("TOKEN", "owner", "repo", "something/else", "")
-  ).rejects.toEqual(new Error("Not a tag: something/else"));
+  ).rejects.toEqual(new Error("Not a tag or branch: something/else"));
 });
 
 test("Invalid semver tag", async () => {
@@ -145,6 +145,11 @@ test("Invalid semver tag", async () => {
   ).rejects.toEqual(new Error("Invalid semver tag: v1"));
 });
 
+test("No ref", async () => {
+  const tags = await calculateTags("TOKEN", "owner", "repo", null, "");
+  expect(tags).toEqual([]);
+});
+
 test("Prefix", async () => {
   const scope = nock("https://api.github.com")
     .get("/repos/owner/repo/tags")
diff --git a/src/index.js b/src/index.js
index d5f9735..f0d6010 100644
--- a/src/index.js
+++ b/src/index.js
@@ -14,13 +14,17 @@ function supportedPrerelease(pre) {
 async function calculateTags(token, owner, repo, ref, prefix) {
   core.debug(`ref: ${ref}`);
 
+  if (!ref) {
+    core.debug("No ref");
+    return [];
+  }
   if (ref.startsWith("refs/heads/")) {
     const branch = ref.substring(11);
-    core.debug(`Branch: branch`);
+    core.debug(`Branch: ${branch}`);
     return [`${prefix}${branch}`];
   }
   if (!ref.startsWith("refs/tags/")) {
-    throw new Error(`Not a tag: ${ref}`);
+    throw new Error(`Not a tag or branch: ${ref}`);
   }
 
   const currentTag = ref.substring(10);