Fix random tag selection if two are equal

Also add tests, add workflow for tests, add CODEOWNERS

Author: csmith

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @csmith

.github/workflows/test.yml

@@ -0,0 +1,11 @@
+name: run go tests
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    uses: csmith/github-workflows/.github/workflows/go-test.yml@master

CHANGELOG.md

@@ -0,0 +1,5 @@
+# v1.1.0 (Fri Jul 30 2021)
+
+- GetLatestTag will now return a stable answer if there are multiple, equivalent
+  tags in the repository (e.g. `refs/tags/v1.0.0` and `refs/tags/1.0.0`). Previously
+  the returned tag would be randomly selected.

go.mod

@@ -1,5 +1,5 @@
 module github.com/csmith/gitrefs
 
-go 1.17
+go 1.20
 
 require github.com/hashicorp/go-version v1.6.0

tags.go

@@ -16,16 +16,23 @@ func LatestTag(url string, options ...Option) (string, string, error) {
 		return "", "", err
 	}
 
+	return latestTag(refs)
+}
+
+func latestTag(refs map[string]string) (string, string, error) {
 	best := version.Must(version.NewVersion("0.0.0"))
 	bestTag := ""
 	bestHash := ""
 	for r := range refs {
 		tag := strings.TrimPrefix(r, tagPrefix)
 		v, err := version.NewVersion(tag)
-		if err == nil && v.GreaterThanOrEqual(best) && v.Prerelease() == "" {
-			best = v
-			bestTag = tag
-			bestHash = refs[r]
+		if err == nil && v.Prerelease() == "" {
+			println(v.Original(), best.Original(), v.GreaterThan(best), v.Equal(best), strings.Compare(v.Original(), best.Original()) < 0)
+			if v.GreaterThan(best) || (v.Equal(best) && strings.Compare(v.Original(), best.Original()) < 0) {
+				best = v
+				bestTag = tag
+				bestHash = refs[r]
+			}
 		}
 	}
 

tags_test.go

@@ -0,0 +1,59 @@
+package gitrefs
+
+import "testing"
+
+const (
+	commit1 = "a1b2c3d4e5f6"
+	commit2 = "f6e5d4c3b2a1"
+	commit3 = "1a2b3c4d5e6f"
+)
+
+func Test_latestTag(t *testing.T) {
+	tests := []struct {
+		name     string
+		args     map[string]string
+		wantTag  string
+		wantHash string
+		wantErr  bool
+	}{
+		{"No refs", map[string]string{}, "", "", true},
+		{"No tags", map[string]string{
+			"refs/heads/master": commit1,
+			"refs/heads/v1.0.0": commit2,
+		}, "", "", true},
+		{"Single tag", map[string]string{
+			"refs/heads/master": commit1,
+			"refs/heads/v1.0.0": commit2,
+			"refs/tags/v1.0.0":  commit3,
+		}, "v1.0.0", commit3, false},
+		{"Multiple tags", map[string]string{
+			"refs/tags/v0.9.9": commit1,
+			"refs/tags/v1.0.0": commit2,
+			"refs/tags/v1.0.1": commit3,
+		}, "v1.0.1", commit3, false},
+		{"Pre-release tags", map[string]string{
+			"refs/tags/v0.9.9":        commit1,
+			"refs/tags/v1.0.0-rc1":    commit2,
+			"refs/tags/v1.0.0-alpha7": commit3,
+		}, "v0.9.9", commit1, false},
+		{"Equal tags", map[string]string{
+			"refs/tags/v1.0.0": commit1,
+			"refs/tags/1.0.0":  commit2,
+		}, "1.0.0", commit2, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tag, hash, err := latestTag(tt.args)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("latestTag() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if tag != tt.wantTag {
+				t.Errorf("latestTag() tag = %v, wantTag %v", tag, tt.wantTag)
+			}
+			if hash != tt.wantHash {
+				t.Errorf("latestTag() hash = %v, wantTag %v", hash, tt.wantHash)
+			}
+		})
+	}
+}