[ASCII-1498] add dependency list test for the serverless binary

cmd/serverless/dependency_list_test.go

@@ -0,0 +1,57 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build test && linux
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const erroMsg = `
+The %s_dependencies_%s.txt file is out of date. 
+Update the file locally with this content: 
+%s
+`
+
+func buildDependencyList() (string, error) {
+	run := "go"
+	arg0 := "list"
+	arg1 := "-f"
+	arg2 := `"{{ join .Deps "\n"}}"`
+	arg3 := "-tags"
+	arg4 := "serverless,otlp"
+	arg5 := "github.com/DataDog/datadog-agent/cmd/serverless"
+	cmd := exec.Command(run, arg0, arg1, arg2, arg3, arg4, arg5)
+
+	stdout, err := cmd.Output()
+	return string(stdout), err
+}
+
+// This test is here to add friction to the process of adding dependencies to the serverless binary.
+// If you are adding a dependency to the serverless binary, you must update the dependencies.txt file.
+// Same for when you remove a dependency.
+// Having this test also allow us to better track additions and removals of dependencies for the serverless binary.
+func TestImportPackage(t *testing.T) {
+	dependencyList, err := buildDependencyList()
+	assert.NoError(t, err)
+	file := fmt.Sprintf("%s_dependencies_%s.txt", runtime.GOOS, runtime.GOARCH)
+
+	data, err := os.ReadFile(file)
+	assert.NoError(t, err)
+
+	cleanDependencyList := strings.TrimLeft(dependencyList, "\"")
+	cleanDependencyList = strings.TrimRight(cleanDependencyList, "\"\n")
+	cleanDependencyList += "\n"
+	assert.Equal(t, string(data), cleanDependencyList, fmt.Sprintf(erroMsg, runtime.GOOS, runtime.GOARCH, cleanDependencyList))
+}