Add internal/kctl and internal/config packages with unit tests

internal/kctl/labels_test.go

@@ -0,0 +1,45 @@
+package kctl
+
+import (
+	"reflect"
+	"testing"
+)
+
+func testNamespaces() map[string]map[string]string {
+	return map[string]map[string]string{
+		"ns-one":   {"team-label": "team-a"},
+		"ns-two":   {"team-label": "team-b"},
+		"ns-three": {"team-label": "team-a"},
+		"ns-four":  {}, // no label at all
+	}
+}
+
+func TestDistinctLabelValues(t *testing.T) {
+	got := DistinctLabelValues(testNamespaces(), "team-label")
+	want := []string{"team-a", "team-b"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+}
+
+func TestDistinctLabelValues_UnknownKey(t *testing.T) {
+	got := DistinctLabelValues(testNamespaces(), "does-not-exist")
+	if len(got) != 0 {
+		t.Fatalf("expected empty result, got %v", got)
+	}
+}
+
+func TestNamespacesForLabelValue(t *testing.T) {
+	got := NamespacesForLabelValue(testNamespaces(), "team-label", "team-a")
+	want := []string{"ns-one", "ns-three"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+}
+
+func TestNamespacesForLabelValue_NoMatch(t *testing.T) {
+	got := NamespacesForLabelValue(testNamespaces(), "team-label", "team-z")
+	if len(got) != 0 {
+		t.Fatalf("expected empty result, got %v", got)
+	}
+}