Add some config tests

Still some more to add

config.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"gopkg.in/yaml.v2"
 	"io/ioutil"
 	"log"
@@ -17,6 +18,12 @@ type Config struct {
 // IsValid checks config validity and returns true if valid
 func (config Config) IsValid() (isValid bool) {
 	isValid = true
+
+	// Validate monitors
+	if config.Monitors == nil || len(config.Monitors) == 0 {
+		log.Printf("ERROR: Invalid monitor configuration: Must provide at least one monitor")
+		isValid = false
+	}
 	for _, monitor := range config.Monitors {
 		if !monitor.IsValid() {
 			log.Printf("ERROR: Invalid monitor configuration: %s", monitor.Name)
@@ -24,6 +31,11 @@ func (config Config) IsValid() (isValid bool) {
 		}
 	}
 
+	// Validate alerts
+	if config.Alerts == nil || len(config.Alerts) == 0 {
+		log.Printf("ERROR: Invalid alert configuration: Must provide at least one alert")
+		isValid = false
+	}
 	for _, alert := range config.Alerts {
 		if !alert.IsValid() {
 			log.Printf("ERROR: Invalid alert configuration: %s", alert.Name)
@@ -35,38 +47,40 @@ func (config Config) IsValid() (isValid bool) {
 }
 
 // Init performs extra initialization on top of loading the config from file
-func (config *Config) Init() {
+func (config *Config) Init() (err error) {
 	for name, alert := range config.Alerts {
 		alert.Name = name
-		if err := alert.BuildTemplates(); err != nil {
-			panic(err)
+		if err = alert.BuildTemplates(); err != nil {
+			return
 		}
 	}
+
+	return
 }
 
 // LoadConfig will read config from the given path and parse it
-func LoadConfig(filePath string) (config Config) {
+func LoadConfig(filePath string) (config Config, err error) {
 	data, err := ioutil.ReadFile(filePath)
 	if err != nil {
-		panic(err)
+		return
 	}
 
 	// TODO: Decide if this is better expanded here, or only when executing
 	envExpanded := os.ExpandEnv(string(data))
 	err = yaml.Unmarshal([]byte(envExpanded), &config)
 	if err != nil {
-		log.Fatalf("ERROR: %v", err)
-		panic(err)
+		return
 	}
 
 	log.Printf("config:\n%v\n", config)
 
 	if !config.IsValid() {
-		panic("Cannot continue with invalid configuration")
+		err = errors.New("Invalid configuration")
+		return
 	}
 
 	// Finish initializing configuration
-	config.Init()
+	err = config.Init()
 
-	return config
+	return
 }

config_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"log"
+	"testing"
+)
+
+func TestLoadConfig(t *testing.T) {
+	cases := []struct {
+		configPath string
+		expectErr  bool
+		name       string
+	}{
+		{"./test/valid-config.yml", false, "Valid config file"},
+		{"./test/does-not-exist", true, "Invalid config path"},
+		{"./test/invalid-config-type.yml", true, "Invalid config type for key"},
+		{"./test/invalid-config-missing-alerts.yml", true, "Invalid config missing alerts"},
+	}
+
+	for _, c := range cases {
+		log.Printf("Testing case %s", c.name)
+		_, err := LoadConfig(c.configPath)
+		hasErr := (err != nil)
+		if hasErr != c.expectErr {
+			t.Errorf("LoadConfig(%v), expected=%v actual=%v", c.name, "Err", err)
+			log.Printf("Case failed: %s", c.name)
+		}
+		log.Println("-----")
+	}
+}

main.go

@@ -6,7 +6,10 @@ import (
 )
 
 func main() {
-	config := LoadConfig("config.yml")
+	config, err := LoadConfig("config.yml")
+	if err != nil {
+		log.Fatalf("Error loading config: %v", err)
+	}
 
 	for {
 		for _, monitor := range config.Monitors {

test/invalid-config-missing-alerts.yml

@@ -0,0 +1,9 @@
+check_interval: 1
+
+monitors:
+  - name: Command
+    command: ['echo', '$PATH']
+    alert_down: [ 'alert_down', 'log_shell', 'log_command' ]
+    # alert_every: -1
+    alert_every: 0
+

test/invalid-config-type.yml

@@ -0,0 +1 @@
+check_interval: woops, I'm not an int!

test/valid-config.yml

@@ -0,0 +1,22 @@
+check_interval: 1
+
+monitors:
+  - name: Command
+    command: ['echo', '$PATH']
+    alert_down: [ 'log_command', 'log_shell' ]
+    alert_every: 0
+  - name: Shell
+    command_shell: >
+      echo 'Some string with stuff';
+      echo 'another line';
+      echo $PATH;
+      exit 1
+    alert_down: [ 'log_command', 'log_shell' ]
+    alert_after: 5
+    alert_every: 0
+
+alerts:
+  log_command:
+    command: [ 'echo', 'regular', '"command!!!"', "{{.MonitorName}}" ]
+  log_shell:
+    command_shell: echo "Failure on {{.MonitorName}} User is $USER"