Refactor for readability

internal/config/config.go

@@ -0,0 +1,25 @@
+package config
+
+import (
+	"encoding/json"
+	"os"
+)
+
+type Config struct {
+	WriteSecret   string `json:"write_secret"`
+	Addr          string `json:"addr"`
+	ChartMaxWatts int    `json:"chart_max_watts"`
+}
+
+func Load(path string) (Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return Config{}, err
+	}
+
+	var cfg Config
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return Config{}, err
+	}
+	return cfg, nil
+}

internal/config/config_test.go

@@ -0,0 +1,27 @@
+package config
+
+import (
+	"os"
+	"testing"
+)
+
+func TestLoad(t *testing.T) {
+	path := t.TempDir() + "/config.json"
+	if err := os.WriteFile(path, []byte(`{"write_secret":"secret","addr":":9090","chart_max_watts":750}`), 0o600); err != nil {
+		t.Fatalf("write config: %v", err)
+	}
+
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatalf("Load returned error: %v", err)
+	}
+	if cfg.WriteSecret != "secret" {
+		t.Fatalf("write_secret = %q, want %q", cfg.WriteSecret, "secret")
+	}
+	if cfg.Addr != ":9090" {
+		t.Fatalf("addr = %q, want %q", cfg.Addr, ":9090")
+	}
+	if cfg.ChartMaxWatts != 750 {
+		t.Fatalf("chart_max_watts = %d, want %d", cfg.ChartMaxWatts, 750)
+	}
+}