Add flux tree command

The `flux tree kustomization` command prints the resources reconciled by the given Kustomization.

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

cmd/flux/tree_kustomization_test.go

@@ -0,0 +1,64 @@
+// +build unit
+
+/*
+Copyright 2021 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"testing"
+)
+
+func TestTree(t *testing.T) {
+	cases := []struct {
+		name       string
+		args       string
+		objectFile string
+		goldenFile string
+	}{
+		{
+			"tree kustomization",
+			"tree kustomization flux-system",
+			"testdata/tree/kustomizations.yaml",
+			"testdata/tree/tree.golden",
+		},
+		{
+			"tree kustomization compact",
+			"tree kustomization flux-system --compact",
+			"testdata/tree/kustomizations.yaml",
+			"testdata/tree/tree-compact.golden",
+		},
+		{
+			"tree kustomization empty",
+			"tree kustomization empty",
+			"testdata/tree/kustomizations.yaml",
+			"testdata/tree/tree-empty.golden",
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			tmpl := map[string]string{
+				"fluxns": allocateNamespace("flux-system"),
+			}
+			testEnv.CreateObjectFile(tc.objectFile, tmpl, t)
+			cmd := cmdTestCase{
+				args:   tc.args + " -n=" + tmpl["fluxns"],
+				assert: assertGoldenTemplateFile(tc.goldenFile, tmpl),
+			}
+			cmd.runTestCmd(t)
+		})
+	}
+}