all: imp tests, docs

internal/aghalg/aghalg.go

@@ -11,8 +11,8 @@ import (
 )
 
 // Coalesce returns the first non-zero value.  It is named after the function
-// COALESCE in SQL except.  If values or all it's elements are empty, it returns
-// a zero value.
+// COALESCE in SQL.  If values or all its elements are empty, it returns a zero
+// value.
 func Coalesce[T comparable](values ...T) (res T) {
 	var zero T
 	for _, v := range values {

internal/aghos/filewalker_internal_test.go

@@ -11,14 +11,17 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-type errFS struct {
-	fs.GlobFS
-}
+// errFS is an fs.FS implementation, method Open of which always returns
+// errFSOpen.
+type errFS struct{}
 
-const errErrFSOpen errors.Error = "this error is always returned"
+// errFSOpen is returned from errGlobFS.Open.
+const errFSOpen errors.Error = "test open error"
 
-func (efs *errFS) Open(name string) (fs.File, error) {
-	return nil, errErrFSOpen
+// Open implements the fs.FS interface for *errGlobFS.  fsys is always nil and
+// err is always errFSOpen.
+func (efs *errFS) Open(name string) (fsys fs.File, err error) {
+	return nil, errFSOpen
 }
 
 func TestWalkerFunc_CheckFile(t *testing.T) {
@@ -33,7 +36,7 @@ func TestWalkerFunc_CheckFile(t *testing.T) {
 
 	t.Run("invalid_argument", func(t *testing.T) {
 		_, ok, err := checkFile(&errFS{}, nil, "")
-		require.ErrorIs(t, err, errErrFSOpen)
+		require.ErrorIs(t, err, errFSOpen)
 
 		assert.False(t, ok)
 	})

internal/aghtest/upstream.go

@@ -62,7 +62,7 @@ func RespondTo(t testing.TB, req *dns.Msg, cl, qt uint16, targ, answer string) (
 			},
 		}
 	default:
-		t.Fatalf("unsupported question type: %s", dns.Type(qt).String())
+		t.Fatalf("unsupported question type: %s", dns.Type(qt))
 	}
 
 	return resp

internal/filtering/safebrowsing_test.go

@@ -74,8 +74,8 @@ func TestSafeBrowsingCache(t *testing.T) {
 	c.hashToHost[hash] = "sub.host.com"
 	assert.Equal(t, -1, c.getCached())
 
-	// Match "sub.host.com" from cache, but another hash for "host.example" is
-	// not in the cache which means that we must get data from server for it.
+	// Match "sub.host.com" from cache.  Another hash for "host.example" is not
+	// in the cache, so get data for it from the server.
 	c.hashToHost = make(map[[32]byte]string)
 	hash = sha256.Sum256([]byte("sub.host.com"))
 	c.hashToHost[hash] = "sub.host.com"

internal/v1/dnssvc/dnssvc.go

@@ -37,7 +37,7 @@ type Config struct {
 	// server addresses.
 	BootstrapServers []string
 
-	// UpstreamServers are the upstream DNS servers to use.
+	// UpstreamServers are the upstream DNS server addresses to use.
 	UpstreamServers []string
 
 	// UpstreamTimeout is the timeout for upstream requests.
@@ -71,7 +71,7 @@ func New(c *Config) (svc *Service, err error) {
 	if len(c.Upstreams) > 0 {
 		upstreams = c.Upstreams
 	} else {
-		upstreams, err = AddressesToUpstreams(
+		upstreams, err = addressesToUpstreams(
 			c.UpstreamServers,
 			c.BootstrapServers,
 			c.UpstreamTimeout,
@@ -99,10 +99,10 @@ func New(c *Config) (svc *Service, err error) {
 	return svc, nil
 }
 
-// AddressesToUpstreams is a wrapper around [upstream.AddressToUpstream].  It
+// addressesToUpstreams is a wrapper around [upstream.AddressToUpstream].  It
 // accepts a slice of addresses and other upstream parameters, and returns a
 // slice of upstreams.
-func AddressesToUpstreams(
+func addressesToUpstreams(
 	upsStrs []string,
 	bootstraps []string,
 	timeout time.Duration,
@@ -153,8 +153,8 @@ func udpAddrs(addrPorts []netip.AddrPort) (udpAddrs []*net.UDPAddr) {
 var _ agh.Service = (*Service)(nil)
 
 // Start implements the [agh.Service] interface for *Service.  svc may be nil.
-// After Start exits, all DNS servers have tried to start, possibly failing and
-// writing error messages to the log.
+// After Start exits, all DNS servers have tried to start, but there is no
+// guarantee that they did.  Errors from the servers are written to the log.
 func (svc *Service) Start() (err error) {
 	if svc == nil {
 		return nil

internal/v1/dnssvc/dnssvc_test.go

@@ -57,6 +57,7 @@ func TestService(t *testing.T) {
 	require.Len(t, gotConf.Addresses, 1)
 
 	addr := gotConf.Addresses[0]
+
 	t.Run("dns", func(t *testing.T) {
 		req := &dns.Msg{
 			MsgHdr: dns.MsgHdr{