Make release template to work on needs (#2099)

It turned out that Helmfile has never had support for release template on `needs`.
This adds that, along with the new end-to-end test suite to verify helmfile template output with snapshot testing involving a real `helmfile build` command.

Ref #2098

test/e2e/template/helmfile/snapshot_test.go

@@ -0,0 +1,50 @@
+package helmfile
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestHelmfileTemplateWithBuildCommand(t *testing.T) {
+	_, filename, _, _ := runtime.Caller(0)
+	projectRoot := filepath.Join(filepath.Dir(filename), "..", "..", "..", "..")
+	helmfileBin := filepath.Join(projectRoot, "helmfile")
+	testdataDir := "testdata"
+
+	entries, err := os.ReadDir(testdataDir)
+	require.NoError(t, err)
+
+	for _, e := range entries {
+		if !e.IsDir() {
+			t.Fatalf("Unexpected type of entry at %s", e.Name())
+		}
+
+		name := e.Name()
+
+		t.Run(name, func(t *testing.T) {
+			inputFile := filepath.Join(testdataDir, name, "input.yaml")
+
+			want, err := os.ReadFile(filepath.Join(testdataDir, name, "output.yaml"))
+			require.NoError(t, err)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+			defer cancel()
+
+			cmd := exec.CommandContext(ctx, helmfileBin, "-f", inputFile, "build")
+			got, err := cmd.CombinedOutput()
+			if err != nil {
+				t.Logf("%s", string(got))
+			}
+			require.NoError(t, err)
+
+			require.Equal(t, string(want), string(got))
+		})
+	}
+}

test/e2e/template/helmfile/testdata/issue_2098_release_template_needs/input.yaml

@@ -0,0 +1,27 @@
+repositories:
+  - name: aservo
+    url: https://aservo.github.io/charts
+
+environments:
+  default:
+
+---
+
+templates:
+  defaults: &defaults
+    name: "{{ .Environment.Name }}-{{`{{ .Release.Labels.service }}`}}"
+    namespace: "{{ .Environment.Name }}"
+
+releases:
+  - chart: aservo/util
+    version: 0.0.1
+    labels:
+      service: shared-resources
+    <<: *defaults
+  - chart: aservo/util
+    version: 0.0.1
+    labels:
+      service: release-resources
+    <<: *defaults
+    needs:
+      - "{{`{{ .Release.Namespace }}`}}-shared-resources"

test/e2e/template/helmfile/testdata/issue_2098_release_template_needs/output.yaml

@@ -0,0 +1,30 @@
+---
+#  Source: input.yaml
+
+filepath: input.yaml
+helmBinary: helm
+environments:
+  default: {}
+repositories:
+- name: aservo
+  url: https://aservo.github.io/charts
+releases:
+- chart: aservo/util
+  version: 0.0.1
+  name: default-shared-resources
+  namespace: default
+  labels:
+    service: shared-resources
+- chart: aservo/util
+  version: 0.0.1
+  needs:
+  - default-shared-resources
+  name: default-release-resources
+  namespace: default
+  labels:
+    service: release-resources
+templates:
+  defaults:
+    name: default-{{ .Release.Labels.service }}
+    namespace: default
+renderedvalues: {}