add unit test

pkg/fleet/installer/setup/common/config.go

@@ -27,7 +27,7 @@ var (
 	datadogConfFile        = filepath.Join(configDir, "datadog.yaml")
 	logsConfFile           = filepath.Join(configDir, "conf.d/configured_at_install_logs.yaml")
 	sparkConfigFile        = filepath.Join(configDir, "conf.d/spark.d/spark.yaml")
-	injectTracerConfigFile = filepath.Join(configDir, "/etc/datadog-agent/inject/tracer.yaml")
+	injectTracerConfigFile = filepath.Join(configDir, "inject/tracer.yaml")
 )
 
 // HostInstaller is a struct that represents the agent agentConfiguration
@@ -61,21 +61,21 @@ type logsConfig struct {
 type LogConfig struct {
 	Type    string `yaml:"type"`
 	Path    string `yaml:"path"`
-	Service string `yaml:"service"`
-	Source  string `yaml:"source"`
+	Service string `yaml:"service,omitempty"`
+	Source  string `yaml:"source,omitempty"`
 }
 
 type sparkConfig struct {
-	InitConfig interface{}     `yaml:"init_config"`
+	InitConfig interface{}     `yaml:"init_config,omitempty"`
 	Instances  []SparkInstance `yaml:"instances"`
 }
 
 // SparkInstance is a struct that represents a single spark instance
 type SparkInstance struct {
 	SparkURL         string `yaml:"spark_url"`
-	SparkClusterMode string `yaml:"spark_cluster_mode"`
+	SparkClusterMode string `yaml:"spark_cluster_mode,omitempty"`
 	ClusterName      string `yaml:"cluster_name"`
-	StreamingMetrics bool   `yaml:"streaming_metrics"`
+	StreamingMetrics bool   `yaml:"streaming_metrics,omitempty"`
 }
 
 type injectorConfig struct {
@@ -100,7 +100,7 @@ func NewHostInstaller(env *env.Env) (*HostInstaller, error) {
 }
 
 func newHostInstaller(env *env.Env, ddUID, ddGID int) (*HostInstaller, error) {
-	i := &HostInstaller{}
+	i := &HostInstaller{agentConfig: make(map[string]interface{})}
 	if env.APIKey == "" {
 		return nil, fmt.Errorf("DD_API key is required")
 	}

pkg/fleet/installer/setup/common/config_test.go

@@ -0,0 +1,61 @@
+// 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 !windows
+
+// Package common contains the HostInstaller struct which is used to write the agent agentConfiguration to disk
+package common
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/DataDog/datadog-agent/pkg/fleet/installer/env"
+)
+
+func assertFileContent(t *testing.T, file, content string) {
+	b, err := os.ReadFile(file)
+	assert.NoError(t, err)
+	assert.Equal(t, content, string(b))
+}
+
+func TestAgentConfigs(t *testing.T) {
+	configDir = t.TempDir()
+	datadogConfFile = filepath.Join(configDir, "datadog.yaml")
+	logsConfFile = filepath.Join(configDir, "conf.d/configured_at_install_logs.yaml")
+	sparkConfigFile = filepath.Join(configDir, "conf.d/spark.d/spark.yaml")
+
+	i, err := newHostInstaller(&env.Env{APIKey: "a"}, 0, 0)
+	assert.NotNil(t, i)
+	assert.Nil(t, err)
+
+	i.AddAgentConfig("key", "value")
+	i.AddLogConfig(LogConfig{Type: "file", Path: "/var/log/app.log", Service: "app"})
+	i.AddHostTag("k1", "v1")
+	i.AddHostTag("k2", "v2")
+	i.AddSparkInstance(SparkInstance{ClusterName: "cluster", SparkURL: "http://localhost:8080"})
+
+	assert.NoError(t, i.writeConfigs())
+	assertFileContent(t, datadogConfFile, `api_key: a
+key: value
+logs_enabled: true
+tags:
+- k1:v1
+- k2:v2
+`)
+
+	assertFileContent(t, logsConfFile, `logs:
+- type: file
+  path: /var/log/app.log
+  service: app
+`)
+	assertFileContent(t, sparkConfigFile, `instances:
+- spark_url: http://localhost:8080
+  cluster_name: cluster
+`)
+}