Configuration Testing Template

Standardized test checklist for configuration loading, validation, and secrets handling. Applies to both the top-level app config and per-provider/source configs.

Philosophy: Configuration errors should fail fast, fail loud, and tell the operator exactly what's wrong.

Test Categories

1. Environment Variables

#	Test	Description	Priority
V1	All required vars	Config loads successfully with all required vars set	Required
V2	Missing required var	Clear error naming the missing variable	Required
V3	Empty string var	Empty string treated as unset for required fields	Required
V4	Default values	Omitted optional vars use documented defaults	Required
V5	Boolean parsing	"true", "1", "yes" all accepted	Recommended
V6	Duration parsing	"10s", "5m", "1h" parsed correctly	Recommended
V7	Integer parsing	Invalid integer → clear error	Recommended
V8	Case sensitivity	Env var names are case-sensitive (standard behavior)	Required

2. YAML / File Config

#	Test	Description	Priority
Y1	Valid YAML	Complete config file loads without error	Required
Y2	Minimal YAML	Only required fields → loads with defaults	Required
Y3	Invalid YAML	Malformed YAML → parse error, not panic	Required
Y4	Unknown fields	Extra YAML fields → warning or ignored (not error)	Recommended
Y5	Type mismatch	String where int expected → clear error	Required
Y6	File not found	Missing config file → clear error with path	Required

3. Validation

#	Test	Description	Priority
D1	Zone format	Zone must end with . → error if missing	Required
D2	Server format	Server address validated (host:port)	Required
D3	TSIG completeness	If any TSIG field set, all required TSIG fields must be set	Required
D4	TSIG algorithm	Unsupported algorithm → error listing valid options	Required
D5	Timeout range	Negative timeout → error	Required
D6	Instance naming	Instance names validated (alphanumeric, hyphens)	Recommended
D7	Duplicate instances	Two instances with same name → error	Recommended
D8	Domain pattern	Provider domain patterns validated	Recommended

4. Secrets

#	Test	Description	Priority
S1	File-based secrets	_FILE suffix reads from file path	Recommended
S2	Secret trimming	Trailing newlines stripped from file secrets	Recommended
S3	Secret not logged	Config String()/log output redacts secrets	Required
S4	Missing secret file	_FILE pointing to non-existent file → clear error	Recommended

5. Multi-Instance

#	Test	Description	Priority
I1	Multiple providers	DNSWEAVER_INSTANCES=a,b loads both	Required
I2	Different types	Mixed provider types in one config	Required
I3	Independent configs	Each instance has its own config namespace	Required
I4	Instance list parsing	Whitespace, trailing commas handled	Recommended

Implementation Pattern

package config_test

import (
    "testing"

    "gitlab.bluewillows.net/root/dnsweaver/internal/config"
)

func TestLoad_MinimalConfig(t *testing.T) {
    t.Setenv("DNSWEAVER_INSTANCES", "test")
    t.Setenv("DNSWEAVER_TEST_TYPE", "technitium")
    t.Setenv("DNSWEAVER_TEST_URL", "http://dns.example.com")
    t.Setenv("DNSWEAVER_TEST_API_KEY", "secret")
    t.Setenv("DNSWEAVER_TEST_ZONE", "example.com.")
    t.Setenv("DNSWEAVER_TEST_DOMAINS", "example.com")

    cfg, err := config.Load()
    if err != nil {
        t.Fatalf("Load: %v", err)
    }
    if len(cfg.Instances) != 1 {
        t.Fatalf("expected 1 instance, got %d", len(cfg.Instances))
    }
}

func TestLoad_MissingRequired(t *testing.T) {
    t.Setenv("DNSWEAVER_INSTANCES", "test")
    // Missing TYPE
    _, err := config.Load()
    if err == nil {
        t.Fatal("expected error for missing type")
    }
}

Validation Error Quality

Config errors should be:

1. Specific — Name the field and what's wrong
2. Aggregated — Report all validation errors at once, not just the first
3. Actionable — Include expected format or valid options
4. Non-panicking — Return errors, never crash

// Good error:
"dnsupdate config validation failed: zone must end with a dot (e.g., 'example.com.')"

// Bad error:
"invalid config"