start pruning reimplementation in cmd/pruning subpackage

cmd/pruning/pruning_test.go

@@ -0,0 +1,88 @@
+package pruning
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+type stubSnap struct {
+	name       string
+	replicated bool
+	date       time.Time
+}
+
+func (s stubSnap) Name() string { return s.name }
+
+func (s stubSnap) Replicated() bool { return s.replicated }
+
+func (s stubSnap) Date() time.Time { return s.date }
+
+func TestPruneSnapshots(t *testing.T) {
+
+	type testCase struct {
+		inputs   []Snapshot
+		rules    []KeepRule
+		exp, eff []Snapshot
+	}
+
+	inputs := map[string][]Snapshot{
+		"s1": []Snapshot{
+			stubSnap{name: "foo_123"},
+			stubSnap{name: "foo_456"},
+			stubSnap{name: "bar_123"},
+		},
+	}
+
+	tcs := map[string]testCase{
+		"simple": {
+			inputs: inputs["s1"],
+			rules: []KeepRule{
+				MustKeepRegex("foo_"),
+			},
+			exp: []Snapshot{
+				stubSnap{name: "bar_123"},
+			},
+		},
+		"multipleRules": {
+			inputs: inputs["s1"],
+			rules: []KeepRule{
+				MustKeepRegex("foo_"),
+				MustKeepRegex("bar_"),
+			},
+			exp: []Snapshot{},
+		},
+		"onlyThoseRemovedByAllAreRemoved": {
+			inputs: inputs["s1"],
+			rules: []KeepRule{
+				MustKeepRegex("notInS1"), // would remove all
+				MustKeepRegex("bar_"),    // would remove all but bar_, i.e. foo_.*
+			},
+			exp: []Snapshot{
+				stubSnap{name: "foo_123"},
+				stubSnap{name: "foo_456"},
+			},
+		},
+		"noRulesKeepsAll": {
+			inputs: inputs["s1"],
+			rules:  []KeepRule{},
+			exp:    inputs["s1"],
+		},
+		"noSnaps": {
+			inputs: []Snapshot{},
+			rules: []KeepRule{
+				MustKeepRegex("foo_"),
+			},
+			exp: []Snapshot{},
+		},
+	}
+
+	for name := range tcs {
+		t.Run(name, func(t *testing.T) {
+			tc := tcs[name]
+			tc.eff = PruneSnapshots(tc.inputs, tc.rules)
+			assert.Equal(t, tc.exp, tc.eff)
+		})
+	}
+
+}