feat: implement a better way to resolve remote and upstream branch (#122)

Co-authored-by: Nick Snyder <[email protected]>

Author: guoyiteng

src/git.ts

@@ -3,6 +3,29 @@ import * as path from 'path'
 import { log } from './log'
 import { getRemoteUrlReplacements } from './config'
 
+/**
+ * Returns [remote, upstream branch].
+ * Empty remote is returned if the upstream branch points to a local branch.
+ * Empty upstream branch is returned if there is no upstream branch.
+ */
+async function gitRemoteBranch(repoDirectory: string): Promise<[string, string]> {
+    try {
+        const { stdout } = await execa('git', ['rev-parse', '--abbrev-ref', 'HEAD@{upstream}'], { cwd: repoDirectory })
+        const remoteAndBranch = stdout.split('/')
+        if (remoteAndBranch.length === 2) {
+            const [remote, branch] = remoteAndBranch
+            return [remote, branch]
+        }
+        if (remoteAndBranch.length === 1) {
+            // The upstream branch points to a local branch.
+            return ['', remoteAndBranch[0]]
+        }
+        return ['', '']
+    } catch {
+        return ['', '']
+    }
+}
+
 /**
  * Returns the names of all git remotes, e.g. ["origin", "foobar"]
  */
@@ -29,9 +52,16 @@ async function gitRemoteURL(repoDirectory: string, remoteName: string): Promise<
 }
 
 /**
- * Returns the remote URL of the first Git remote found.
+ * Returns the remote URL.
  */
 async function gitDefaultRemoteURL(repoDirectory: string): Promise<string> {
+    const [remote] = await gitRemoteBranch(repoDirectory)
+    if (remote !== '') {
+        return gitRemoteURL(repoDirectory, remote)
+    }
+
+    // If we cannot find the remote name deterministically, we use the first
+    // Git remote found.
     const remotes = await gitRemotes(repoDirectory)
     if (remotes.length === 0) {
         throw new Error('no configured git remotes')
@@ -52,12 +82,17 @@ async function gitRootDirectory(repoDirectory: string): Promise<string> {
 }
 
 /**
- * Returns either the current branch name of the repository OR in all
- * other cases (e.g. detached HEAD state), it returns "HEAD".
+ * Returns either the current remote branch name of the repository OR in all
+ * other cases (e.g. detached HEAD state, upstream branch points to a local
+ * branch), it returns "HEAD".
  */
 async function gitBranch(repoDirectory: string): Promise<string> {
-    const { stdout } = await execa('git', ['rev-parse', '--abbrev-ref', 'HEAD'], { cwd: repoDirectory })
-    return stdout
+    const [origin, branch] = await gitRemoteBranch(repoDirectory)
+    if (origin !== '') {
+        // The remote branch exists.
+        return branch
+    }
+    return 'HEAD'
 }
 
 /**