Fix branch name detection

mage/git.go

@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"sort"
 	"strings"
 	"sync"
 
@@ -78,24 +79,53 @@ func getVersion() string {
 	return "v0.0.0"
 }
 
-// Get the name of the current branch, or the branch that contains the current tag
+// Return either "main", "v*", or "dev" for all other branches.
 func getBranchName() string {
-	// pull request
-	if branch, ok := os.LookupEnv("SYSTEM_PULLREQUEST_SOURCEBRANCH"); ok {
-		return branch
+	gitOutput, _ := must.OutputS("git", "for-each-ref", "--contains", "HEAD", "--format=%(refname)")
+	refs := strings.Split(gitOutput, "\n")
+
+	return pickBranchName(refs)
+}
+
+// Return either "main", "v*", or "dev" for all other branches.
+func pickBranchName(refs []string) string {
+	var branch string
+
+	if b, ok := os.LookupEnv("SYSTEM_PULLREQUEST_SOURCEBRANCH"); ok {
+		// pull request
+		branch = b
+	} else if b, ok := os.LookupEnv("BUILD_SOURCEBRANCHNAME"); ok {
+		// branch build
+		branch = b
+	} else {
+		// tag build
+		// Detect if this was a tag on main or a release
+		sort.Strings(refs) // put main ahead of release/v*
+		for _, ref := range refs {
+			// Ignore tags
+			if strings.HasSuffix(ref, "refs/tags") {
+				continue
+			}
+
+			// Only match main and release/v* branches
+			if strings.HasSuffix(ref, "/main") || strings.Contains(ref, "/release/v") {
+				branch = ref
+				break
+			}
+		}
 	}
 
-	// branch build
-	if branch, ok := os.LookupEnv("BUILD_SOURCEBRANCHNAME"); ok {
-		return branch
+	// Convert the ref name into a branch name, e.g. refs/heads/main -> main
+	branch = strings.NewReplacer("refs/heads/", "", "refs/remotes/origin/", "").Replace(branch)
+
+	// Only use the following branch names "main", "release/v*", and "dev" for everything else
+	if branch != "main" && !strings.HasPrefix(branch, "release/v") {
+		branch = "dev"
 	}
 
-	// tag build
-	// Use the first branch that contains the current commit
-	matches, _ := must.OutputS("git", "for-each-ref", "--contains", "HEAD", "--format=%(refname:short)")
-	firstMatchingBranch := strings.Split(matches, "\n")[0]
-	// The matching branch may be a remote branch, just get its name
-	return strings.Replace(firstMatchingBranch, "origin/", "", 1)
+	// Convert release/v1 -> v1
+	branch = strings.ReplaceAll(branch, "release/", "")
+	return branch
 }
 
 func getPermalink() (string, bool) {
@@ -116,7 +146,7 @@ func getPermalink() (string, bool) {
 	// Get the current branch name, or the name of the branch we tagged from
 	branch := getBranchName()
 
-	// Build a permalink such as "canary", "latest", "latest-v1", or "canary-v1"
+	// Build a permalink such as "canary", "latest", "latest-v1", or "dev-canary"
 	switch branch {
 	case "main":
 		return permalinkPrefix, taggedRelease

mage/git_test.go

@@ -0,0 +1,89 @@
+package mage
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPickBranchName(t *testing.T) {
+	// These aren't set locally but are set on a CI run
+	os.Unsetenv("SYSTEM_PULLREQUEST_SOURCEBRANCH")
+	os.Unsetenv("BUILD_SOURCEBRANCHNAME")
+
+	t.Run("origin/main", func(t *testing.T) {
+		refs := []string{
+			"refs/heads/foo",
+			"refs/remotes/origin/main",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+			"refs/tags/v0.38.3",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "main", branch)
+	})
+
+	t.Run("main", func(t *testing.T) {
+		refs := []string{
+			"refs/heads/foo",
+			"refs/heads/main",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+			"refs/tags/v0.38.3",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "main", branch)
+	})
+
+	t.Run("pull request", func(t *testing.T) {
+		os.Setenv("SYSTEM_PULLREQUEST_SOURCEBRANCH", "patch-1")
+		defer os.Unsetenv("SYSTEM_PULLREQUEST_SOURCEBRANCH")
+
+		refs := []string{
+			"refs/remotes/origin/foo",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "dev", branch)
+	})
+
+	t.Run("branch build", func(t *testing.T) {
+		os.Setenv("BUILD_SOURCEBRANCHNAME", "foo")
+		defer os.Unsetenv("BUILD_SOURCEBRANCHNAME")
+
+		refs := []string{
+			"refs/remotes/origin/foo",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "dev", branch)
+	})
+
+	t.Run("tagged release on v1", func(t *testing.T) {
+		refs := []string{
+			"refs/heads/release/v1",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+			"refs/tags/v1.0.0-alpha.1",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "v1", branch)
+	})
+
+	t.Run("tagged release on main", func(t *testing.T) {
+		refs := []string{
+			"refs/heads/release/v1",
+			"refs/heads/main",
+			"refs/remotes/origin/8252b6e4b1983702c7387ece7f971ef74047b746",
+			"refs/tags/v0.38.3",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "main", branch)
+	})
+
+	t.Run("local branch", func(t *testing.T) {
+		refs := []string{
+			"refs/heads/foo",
+		}
+		branch := pickBranchName(refs)
+		assert.Equal(t, "dev", branch)
+	})
+}