Fixed lint issues and missing documentation

internal/config/section_test.go

@@ -33,7 +33,7 @@ type testSection struct {
 	NoTag    string
 	Skipped  string `cfg:"-"`
 	Empty    string `cfg:""`
-	unexport string `cfg:"unexported"`
+	unexport string `cfg:"unexported"` //nolint:unused // checks unexported fields are ignored
 }
 
 type testValidated struct {
@@ -85,6 +85,9 @@ func TestMapOf(t *testing.T) {
 	if got := m["on"]; got != true {
 		t.Errorf("m[on] (promoted) = %#v", got)
 	}
+	if got := m["dur"]; got != "1m30s" {
+		t.Errorf("m[dur] = %#v; want the duration as a string", got)
+	}
 	inner, ok := m["inner"].(map[string]any)
 	if !ok {
 		t.Fatalf("m[inner] = %#v; want nested map", m["inner"])
@@ -102,12 +105,15 @@ func TestMapOf(t *testing.T) {
 }
 
 func TestFlattenOfPrefix(t *testing.T) {
-	m := flattenOf("p", testSection{})
+	m := flattenOf("p", testSection{Dur: 90 * time.Second})
 	for _, k := range []string{"p.str", "p.on", "p.inner.name"} {
 		if _, ok := m[k]; !ok {
 			t.Errorf("flattenOf missing %q in %v", k, m)
 		}
 	}
+	if got := m["p.dur"]; got != "1m30s" {
+		t.Errorf("m[p.dur] = %#v; want the duration as a string", got)
+	}
 }
 
 func TestStructValuePanics(t *testing.T) {
@@ -220,12 +226,12 @@ func TestSetValue(t *testing.T) {
 		{"uint16", "65535", uint16(65535)},
 		{"float", "2.25", 2.25},
 		{"float32", "0.5", float32(0.5)},
-		{"dur", "1h30m", 90 * time.Minute},
+		{"dur", "1h30m", "1h30m0s"}, // durations are given out as strings
 		{"inner.name", "nested", "nested"},
 		// values of the field's type are used as-is
 		{"int", 5, 5},
 		{"on", true, true},
-		{"dur", 3 * time.Second, 3 * time.Second},
+		{"dur", 3 * time.Second, "3s"},
 		{"slice", []string{"a", "b"}, []string{"a", "b"}},
 		{"when", time.Unix(0, 0).UTC(), time.Unix(0, 0).UTC()},
 	}