Stop startup when a setting does not parse (closes #219)

config.New read the number and true/false settings with viper's
GetInt, GetFloat64 and GetBool. These return zero or false for a value
that does not parse, so a typo silently changed how the server ran.

config.New now parses these settings with strconv. It also checks that
MESSAGE_MAX_AGE, QUEUE_MAX_AGE and SESSION_IDLE_TIMEOUT are valid Go
durations. A value that does not parse makes config.New return an
error naming the setting and its value, and startup stops. Unset
settings keep their defaults.

Model: opus-5-5

internal/config/config_test.go

@@ -2,6 +2,7 @@ package config_test
 
 import (
 	"os"
+	"strings"
 	"testing"
 	"time"
 
@@ -10,7 +11,8 @@ import (
 	"sneak.berlin/go/neoirc/internal/logger"
 )
 
-func newConfig(t *testing.T) *config.Config {
+// loadConfig runs config.New and returns its result.
+func loadConfig(t *testing.T) (*config.Config, error) {
 	t.Helper()
 
 	globs := &globals.Globals{
@@ -24,9 +26,15 @@ func newConfig(t *testing.T) *config.Config {
 		t.Fatal(err)
 	}
 
-	cfg, err := config.New(
+	return config.New(
 		nil, config.Params{Globals: globs, Logger: log},
 	)
+}
+
+func newConfig(t *testing.T) *config.Config {
+	t.Helper()
+
+	cfg, err := loadConfig(t)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -34,6 +42,137 @@ func newConfig(t *testing.T) *config.Config {
 	return cfg
 }
 
+func TestUnsetSettingsKeepDefaults(t *testing.T) {
+	// Viper counts an empty environment variable as unset.
+	t.Setenv("PORT", "")
+	t.Setenv("MAX_MESSAGE_SIZE", "")
+	t.Setenv("NEOIRC_HASHCASH_BITS", "")
+	t.Setenv("LOGIN_RATE_BURST", "")
+	t.Setenv("LOGIN_RATE_LIMIT", "")
+	t.Setenv("DEBUG", "")
+	t.Setenv("MAINTENANCE_MODE", "")
+	t.Setenv("MESSAGE_MAX_AGE", "")
+	t.Setenv("QUEUE_MAX_AGE", "")
+	t.Setenv("SESSION_IDLE_TIMEOUT", "")
+
+	// Each duration setting defaults to 30 days.
+	const thirtyDays = "720h"
+
+	want := settings{
+		Port:               8080,
+		MaxMessageSize:     4096,
+		HashcashBits:       20,
+		LoginRateBurst:     5,
+		LoginRateLimit:     1,
+		Debug:              false,
+		MaintenanceMode:    false,
+		MessageMaxAge:      thirtyDays,
+		QueueMaxAge:        thirtyDays,
+		SessionIdleTimeout: thirtyDays,
+	}
+
+	got := settingsOf(newConfig(t))
+	if got != want {
+		t.Errorf("settings = %+v, want %+v", got, want)
+	}
+}
+
+func TestValidSettingsAreUsed(t *testing.T) {
+	t.Setenv("PORT", "9000")
+	t.Setenv("MAX_MESSAGE_SIZE", "1024")
+	t.Setenv("NEOIRC_HASHCASH_BITS", "0")
+	t.Setenv("LOGIN_RATE_BURST", "10")
+	t.Setenv("LOGIN_RATE_LIMIT", "0.5")
+	t.Setenv("DEBUG", "true")
+	t.Setenv("MAINTENANCE_MODE", "true")
+	t.Setenv("MESSAGE_MAX_AGE", "24h")
+	t.Setenv("QUEUE_MAX_AGE", "1h30m")
+	t.Setenv("SESSION_IDLE_TIMEOUT", "0")
+
+	want := settings{
+		Port:               9000,
+		MaxMessageSize:     1024,
+		HashcashBits:       0,
+		LoginRateBurst:     10,
+		LoginRateLimit:     0.5,
+		Debug:              true,
+		MaintenanceMode:    true,
+		MessageMaxAge:      "24h",
+		QueueMaxAge:        "1h30m",
+		SessionIdleTimeout: "0",
+	}
+
+	got := settingsOf(newConfig(t))
+	if got != want {
+		t.Errorf("settings = %+v, want %+v", got, want)
+	}
+}
+
+// settings holds the Config fields whose settings config.New parses.
+type settings struct {
+	Port               int
+	MaxMessageSize     int
+	HashcashBits       int
+	LoginRateBurst     int
+	LoginRateLimit     float64
+	Debug              bool
+	MaintenanceMode    bool
+	MessageMaxAge      string
+	QueueMaxAge        string
+	SessionIdleTimeout string
+}
+
+func settingsOf(cfg *config.Config) settings {
+	return settings{
+		Port:               cfg.Port,
+		MaxMessageSize:     cfg.MaxMessageSize,
+		HashcashBits:       cfg.HashcashBits,
+		LoginRateBurst:     cfg.LoginRateBurst,
+		LoginRateLimit:     cfg.LoginRateLimit,
+		Debug:              cfg.Debug,
+		MaintenanceMode:    cfg.MaintenanceMode,
+		MessageMaxAge:      cfg.MessageMaxAge,
+		QueueMaxAge:        cfg.QueueMaxAge,
+		SessionIdleTimeout: cfg.SessionIdleTimeout,
+	}
+}
+
+func TestUnparseableSettingStopsStartup(t *testing.T) {
+	tests := []struct {
+		key   string
+		value string
+	}{
+		{key: "PORT", value: "80a"},
+		{key: "MAX_MESSAGE_SIZE", value: "4k"},
+		{key: "NEOIRC_HASHCASH_BITS", value: "twenty"},
+		{key: "LOGIN_RATE_BURST", value: "five"},
+		{key: "LOGIN_RATE_LIMIT", value: "fast"},
+		{key: "DEBUG", value: "yes"},
+		{key: "MAINTENANCE_MODE", value: "on"},
+		{key: "MESSAGE_MAX_AGE", value: "30d"},
+		{key: "QUEUE_MAX_AGE", value: "720"},
+		{key: "SESSION_IDLE_TIMEOUT", value: "a month"},
+	}
+
+	for _, test := range tests {
+		t.Run(test.key, func(t *testing.T) {
+			t.Setenv(test.key, test.value)
+
+			_, err := loadConfig(t)
+			if err == nil {
+				t.Fatalf("%s=%q: got no error", test.key, test.value)
+			}
+
+			msg := err.Error()
+			if !strings.Contains(msg, test.key) ||
+				!strings.Contains(msg, test.value) {
+				t.Errorf("error %q does not name %s and %q",
+					msg, test.key, test.value)
+			}
+		})
+	}
+}
+
 func TestIRCListenAddrUnsetKeepsDefault(t *testing.T) {
 	// t.Setenv puts back whatever value was there after the test.
 	t.Setenv("IRC_LISTEN_ADDR", "")