feat: add support for collections (#2)

Author: juan131

README.md

@@ -1,7 +1,7 @@
 # go-version
 
 [![Go Report Card](https://goreportcard.com/badge/github.com/bitnami/go-version)](https://goreportcard.com/report/github.com/bitnami/go-version)
-[![CI](https://github.com/bitnami/gonit/actions/workflows/go.yml/badge.svg)](https://github.com/bitnami/gonit/actions/workflows/go.yml)
+[![CI](https://github.com/bitnami/go-version/actions/workflows/go.yml/badge.svg)](https://github.com/bitnami/go-version/actions/workflows/go.yml)
 
 go-version is a library for parsing Bitnami packages versions and version constraints, and verifying versions against a set of constraints.
 
@@ -10,6 +10,7 @@ go-version is a library for parsing Bitnami packages versions and version constr
 
 - [Usage](#usage)
   - [Version parsing and comparison](#version-parsing-and-comparison)
+  - [Sorting](#sorting)
   - [Version constraints](#version-constraints)
     - [Version revision](#version-revision)
     - [Missing major/minor/patch versions](#missing-majorminorpatch-versions)
@@ -37,6 +38,22 @@ if v1.LessThan(v2) {
 }
 ```
 
+### Sorting
+
+Collections of versions can be sorted using the `sort.Sort` function from the standard library.
+
+```go
+versionsRaw := []string{"1.1.0", "0.7.1", "1.4.0", "1.4.0-alpha", "1.4.1-beta", "1.4.0-alpha.2+20130313144700"}
+versions := make(version.Collection, len(versionsRaw))
+for i, raw := range versionsRaw {
+    v, _ := version.Parse(raw)
+    versions[i] = v
+}
+
+// After this, the versions are properly sorted
+sort.Sort(versions)
+```
+
 ### Version constraints
 
 Comma-separated version constraints are considered an `AND`. For example, `>= 1.2.3, < 2.0.0` means the version needs to be greater than or equal to `1.2` and less than `3.0.0`.

pkg/version/version_collection.go

@@ -0,0 +1,17 @@
+package version
+
+// Collection is a type that implements the sort.Interface interface
+// so that versions can be sorted.
+type Collection []Version
+
+func (v Collection) Len() int {
+	return len(v)
+}
+
+func (v Collection) Less(i, j int) bool {
+	return v[i].LessThan(v[j])
+}
+
+func (v Collection) Swap(i, j int) {
+	v[i], v[j] = v[j], v[i]
+}

pkg/version/version_collection_test.go

@@ -0,0 +1,80 @@
+package version
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCollection(t *testing.T) {
+	tests := []struct {
+		name     string
+		versions []string
+		want     []string
+	}{
+		{
+			name: "happy path",
+			versions: []string{
+				"1.1.1",
+				"1.0.0",
+				"1.2.0",
+				"2.0.0",
+				"0.7.1",
+			},
+			want: []string{
+				"0.7.1",
+				"1.0.0",
+				"1.1.1",
+				"1.2.0",
+				"2.0.0",
+			},
+		},
+		{
+			name: "revisions",
+			versions: []string{
+				"1.0.0-1.1",
+				"1.0.0-3.1",
+				"1.0.0",
+				"1.0.0-2.2",
+				"1.0.0-2.11",
+				"1.0.0-1",
+				"1.0.0-1.2",
+				"1.0.0-2",
+			},
+			want: []string{
+				"1.0.0",
+				"1.0.0-1",
+				"1.0.0-1.1",
+				"1.0.0-1.2",
+				"1.0.0-2",
+				"1.0.0-2.2",
+				"1.0.0-2.11",
+				"1.0.0-3.1",
+			},
+		},
+	}
+	t.Parallel()
+	for _, testToRun := range tests {
+		test := testToRun
+		t.Run(test.name, func(tt *testing.T) {
+			tt.Parallel()
+			versions := make(Collection, len(test.versions))
+			for i, raw := range test.versions {
+				v, err := Parse(raw)
+				require.NoError(tt, err)
+				versions[i] = v
+			}
+
+			sort.Sort(versions)
+
+			got := make([]string, len(versions))
+			for i, v := range versions {
+				got[i] = v.String()
+			}
+
+			assert.Equal(tt, test.want, got)
+		})
+	}
+}