From 7fae5b61fed27ab1ec1c76592ec31cb6a9d4616b Mon Sep 17 00:00:00 2001
From: Lucas Bajolet <lucas.bajolet@hashicorp.com>
Date: Thu, 5 Sep 2024 15:58:50 -0400
Subject: [PATCH] packer_test: add base tests for DAG eval

Since we introduce the DAG with this series of commits, only on locals
and data sources, we need to make sure that the behaviour is what we
expect.

Therefore, this commit adds a basic test with Packer build, and packer
validate, to evaluate a template with both locals and data sources
depending on one another.

This is rejected with the sequential evaluation methods, as we process
the different types one-by-one, whereas the DAG allows us to mix the
order between the two, while still rejecting circular dependencies (and
doing that before they even get evaluated), and self-references.
---
 packer_test/dag_tests/mix_data_locals_test.go | 26 +++++++++++++++++++
 packer_test/dag_tests/suite_test.go           | 23 ++++++++++++++++
 .../templates/mixed_data_local.pkr.hcl        | 23 ++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 packer_test/dag_tests/mix_data_locals_test.go
 create mode 100644 packer_test/dag_tests/suite_test.go
 create mode 100644 packer_test/dag_tests/templates/mixed_data_local.pkr.hcl

diff --git a/packer_test/dag_tests/mix_data_locals_test.go b/packer_test/dag_tests/mix_data_locals_test.go
new file mode 100644
index 00000000000..8ec19711d54
--- /dev/null
+++ b/packer_test/dag_tests/mix_data_locals_test.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/packer/packer_test/lib"
+)
+
+func (ts *PackerDAGTestSuite) TestWithBothDataLocalMixedOrder() {
+	pluginDir, cleanup := ts.MakePluginDir()
+	defer cleanup()
+
+	for _, cmd := range []string{"build", "validate"} {
+		ts.Run(fmt.Sprintf("%s: evaluating with DAG - success expected", cmd), func() {
+			ts.PackerCommand().UsePluginDir(pluginDir).
+				SetArgs(cmd, "./templates/mixed_data_local.pkr.hcl").
+				Assert(lib.MustSucceed())
+		})
+
+		ts.Run(fmt.Sprintf("%s: evaluating sequentially - failure expected", cmd), func() {
+			ts.PackerCommand().UsePluginDir(pluginDir).
+				SetArgs(cmd, "--use-sequential-evaluation", "./templates/mixed_data_local.pkr.hcl").
+				Assert(lib.MustFail())
+		})
+	}
+}
diff --git a/packer_test/dag_tests/suite_test.go b/packer_test/dag_tests/suite_test.go
new file mode 100644
index 00000000000..f9cdce19bfd
--- /dev/null
+++ b/packer_test/dag_tests/suite_test.go
@@ -0,0 +1,23 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/hashicorp/packer/packer_test/lib"
+	"github.com/stretchr/testify/suite"
+)
+
+type PackerDAGTestSuite struct {
+	*lib.PackerTestSuite
+}
+
+func Test_PackerDAGSuite(t *testing.T) {
+	baseSuite, cleanup := lib.PackerCoreSuite(t)
+	defer cleanup()
+
+	ts := &PackerDAGTestSuite{
+		baseSuite,
+	}
+
+	suite.Run(t, ts)
+}
diff --git a/packer_test/dag_tests/templates/mixed_data_local.pkr.hcl b/packer_test/dag_tests/templates/mixed_data_local.pkr.hcl
new file mode 100644
index 00000000000..a0447538eb2
--- /dev/null
+++ b/packer_test/dag_tests/templates/mixed_data_local.pkr.hcl
@@ -0,0 +1,23 @@
+data "null" "head" {
+	input = "foo"
+}
+
+locals {
+	loc = "${data.null.head.output}"
+}
+
+data "null" "tail" {
+	input = "${local.loc}"
+}
+
+locals {
+	last = "final - ${data.null.tail.output}"
+}
+
+source "null" "test" {
+	communicator = "none"
+}
+
+build {
+	sources = ["null.test"]
+}