fix: not modify the original version (#4)

pkg/version/version.go

@@ -143,6 +143,8 @@ func (v Version) Original() string {
 // It works like Gem::Version.bump()
 // https://docs.ruby-lang.org/en/2.6.0/Gem/Version.html#method-i-bump
 func (v Version) PessimisticBump() Version {
+	v = v.copy()
+
 	size := len(v.segments)
 	if size == 1 {
 		v.segments[0] += 1
@@ -161,6 +163,8 @@ func (v Version) PessimisticBump() Version {
 // TildeBump returns the maximum version of "~"
 // https://docs.npmjs.com/cli/v6/using-npm/semver#tilde-ranges-123-12-1
 func (v Version) TildeBump() Version {
+	v = v.copy()
+
 	if len(v.segments) == 2 {
 		v.segments[1] += 1
 		return v
@@ -172,6 +176,8 @@ func (v Version) TildeBump() Version {
 // CaretBump returns the maximum version of "^"
 // https://docs.npmjs.com/cli/v6/using-npm/semver#caret-ranges-123-025-004
 func (v Version) CaretBump() Version {
+	v = v.copy()
+
 	found := -1
 	for i, s := range v.segments {
 		if s != 0 {
@@ -197,3 +203,15 @@ func (v Version) CaretBump() Version {
 
 	return v
 }
+
+func (v Version) copy() Version {
+	segments := make([]part.Uint64, len(v.segments))
+	copy(segments, v.segments)
+
+	return Version{
+		segments:      segments,
+		preRelease:    v.preRelease,
+		buildMetadata: v.buildMetadata,
+		original:      v.original,
+	}
+}

pkg/version/version_collection_test.go

@@ -77,5 +77,59 @@ func TestCollection(t *testing.T) {
 			assert.Equal(t, tt.want, got)
 		})
 	}
+}
+
+func TestCollection_Constraints(t *testing.T) {
+	tests := []struct {
+		name        string
+		versions    []string
+		constraints string
+		want        string
+	}{
+		{
+			name:        "pessimistic constraints",
+			versions:    []string{"3.0.0", "3.1.0", "3.1.1", "3.1.2", "3.1.3", "3.2.0", "4.0.0"},
+			constraints: "~> 3.0",
+			want:        "3.2.0",
+		},
+		{
+			name:        "caret constraints",
+			versions:    []string{"3.0.0", "3.1.0", "3.1.1", "3.1.2", "3.1.3", "3.2.0", "4.0.0"},
+			constraints: "^3.1",
+			want:        "3.2.0",
+		},
+		{
+			name:        "tilde constraints",
+			versions:    []string{"3.0.0", "3.1.0", "3.1.1", "3.1.2", "3.1.3", "3.2.0", "4.0.0"},
+			constraints: "~ 3.1",
+			want:        "3.1.3",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			constraints, err := NewConstraints(tt.constraints)
+			require.NoError(t, err)
 
+			expected, err := Parse(tt.want)
+			require.NoError(t, err)
+
+			versions := make([]Version, len(tt.versions))
+			for i, raw := range tt.versions {
+				v, err := Parse(raw)
+				require.NoError(t, err)
+				versions[i] = v
+			}
+
+			sort.Sort(sort.Reverse(Collection(versions)))
+
+			for _, ver := range versions {
+				if constraints.Check(ver) {
+					assert.Equal(t, expected, ver)
+					return
+				}
+			}
+
+			t.Fatalf("failed to satisfy %s", tt.constraints)
+		})
+	}
 }