Add Versions.Sort

Sort versions from newest to oldest.

plugin/discovery/version.go

@@ -1,6 +1,8 @@
 package discovery
 
 import (
+	"sort"
+
 	version "github.com/hashicorp/go-version"
 )
 
@@ -45,3 +47,12 @@ func (v Version) String() string {
 func (v Version) NewerThan(other Version) bool {
 	return v.raw.GreaterThan(other.raw)
 }
+
+type Versions []Version
+
+// Sort sorts version from newest to oldest.
+func (v Versions) Sort() {
+	sort.Slice(v, func(i, j int) bool {
+		return v[i].NewerThan(v[j])
+	})
+}

plugin/discovery/version_test.go

@@ -0,0 +1,39 @@
+package discovery
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestSortVersions(t *testing.T) {
+	versions := Versions{
+		VersionStr("4").MustParse(),
+		VersionStr("3.1").MustParse(),
+		VersionStr("1.2").MustParse(),
+		VersionStr("1.2.3").MustParse(),
+		VersionStr("2.2.3").MustParse(),
+		VersionStr("3.2.1").MustParse(),
+		VersionStr("2.3.2").MustParse(),
+	}
+
+	expected := []string{
+		"4.0.0",
+		"3.2.1",
+		"3.1.0",
+		"2.3.2",
+		"2.2.3",
+		"1.2.3",
+		"1.2.0",
+	}
+
+	versions.Sort()
+
+	var sorted []string
+	for _, v := range versions {
+		sorted = append(sorted, v.String())
+	}
+
+	if !reflect.DeepEqual(sorted, expected) {
+		t.Fatal("versions aren't sorted:", sorted)
+	}
+}