Rename determineMergeBaseCommitOid()

The name suggests that the function computes the merge base, which for
Git means specifically the best common ancestors between multiple
commits or branches (see `git merge-base`).

But what the function actually does is to calculate the HEAD commit of
the PR base branch, as derived from the PR merge commit that the action
analyzes. So even though the function has to do with "merge" and "base",
using the term "merge base" is still misleading at best.

This commit renames the function to determineBaseBranchHeadCommitOid(),
which more clearly indicates what the function does.

src/actions-util.test.ts

@@ -269,26 +269,26 @@ test("isAnalyzingDefaultBranch()", async (t) => {
   });
 });
 
-test("determineMergeBaseCommitOid non-pullrequest", async (t) => {
+test("determineBaseBranchHeadCommitOid non-pullrequest", async (t) => {
   const infoStub = sinon.stub(core, "info");
 
   process.env["GITHUB_EVENT_NAME"] = "hucairz";
   process.env["GITHUB_SHA"] = "100912429fab4cb230e66ffb11e738ac5194e73a";
-  const result = await actionsUtil.determineMergeBaseCommitOid(__dirname);
+  const result = await actionsUtil.determineBaseBranchHeadCommitOid(__dirname);
   t.deepEqual(result, undefined);
   t.deepEqual(0, infoStub.callCount);
 
   infoStub.restore();
 });
 
-test("determineMergeBaseCommitOid not git repository", async (t) => {
+test("determineBaseBranchHeadCommitOid not git repository", async (t) => {
   const infoStub = sinon.stub(core, "info");
 
   process.env["GITHUB_EVENT_NAME"] = "pull_request";
   process.env["GITHUB_SHA"] = "100912429fab4cb230e66ffb11e738ac5194e73a";
 
   await withTmpDir(async (tmpDir) => {
-    await actionsUtil.determineMergeBaseCommitOid(tmpDir);
+    await actionsUtil.determineBaseBranchHeadCommitOid(tmpDir);
   });
 
   t.deepEqual(1, infoStub.callCount);
@@ -301,12 +301,12 @@ test("determineMergeBaseCommitOid not git repository", async (t) => {
   infoStub.restore();
 });
 
-test("determineMergeBaseCommitOid other error", async (t) => {
+test("determineBaseBranchHeadCommitOid other error", async (t) => {
   const infoStub = sinon.stub(core, "info");
 
   process.env["GITHUB_EVENT_NAME"] = "pull_request";
   process.env["GITHUB_SHA"] = "100912429fab4cb230e66ffb11e738ac5194e73a";
-  const result = await actionsUtil.determineMergeBaseCommitOid(
+  const result = await actionsUtil.determineBaseBranchHeadCommitOid(
     path.join(__dirname, "../../i-dont-exist"),
   );
   t.deepEqual(result, undefined);

src/actions-util.ts

@@ -108,10 +108,12 @@ export const getCommitOid = async function (
 };
 
 /**
- * If the action was triggered by a pull request, determine the commit sha of the merge base.
- * Returns undefined if run by other triggers or the merge base cannot be determined.
+ * If the action was triggered by a pull request, determine the commit sha at
+ * the head of the base branch, using the merge commit that this workflow analyzes.
+ * Returns undefined if run by other triggers or the base branch commit cannot be
+ * determined.
  */
-export const determineMergeBaseCommitOid = async function (
+export const determineBaseBranchHeadCommitOid = async function (
   checkoutPathOverride?: string,
 ): Promise<string | undefined> {
   if (getWorkflowEventName() !== "pull_request") {

src/upload-lib.ts

@@ -609,7 +609,7 @@ export async function uploadFiles(
     checkoutURI,
     environment,
     toolNames,
-    await actionsUtil.determineMergeBaseCommitOid(),
+    await actionsUtil.determineBaseBranchHeadCommitOid(),
   );
 
   // Log some useful debug info about the info