fix: bad slice allocation

Also add test for futur non-regression
fixes #8

pkg/semver/semver.go

@@ -46,15 +46,15 @@ func (b *Bump) IncPatch() {
 }
 
 func Latest(tags []string) (string, error) {
-	vs := make(semver.Collection, len(tags))
+	vs := make(semver.Collection, 0, len(tags))
 
-	for i, r := range tags {
+	for _, r := range tags {
 		v, err := semver.NewVersion(r)
 		if err != nil {
 			continue
 		}
 
-		vs[i] = v
+		vs = append(vs, v)
 	}
 
 	latest := vs[0]

pkg/semver/semver_test.go

@@ -0,0 +1,49 @@
+package semver
+
+import "testing"
+
+func TestLatest(t *testing.T) {
+	type args struct {
+		tags []string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "one tag",
+			args: args{
+				tags: []string{
+					"v1.0.0",
+				},
+			},
+			want:    "v1.0.0",
+			wantErr: false,
+		},
+		{
+			name: "two tags",
+			args: args{
+				tags: []string{
+					"v1.0.0",
+					"v2.0.0-rc.1",
+				},
+			},
+			want:    "v2.0.0-rc.1",
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := Latest(tt.args.tags)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Latest() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("Latest() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}