Grand test fixup (#138)

* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig

vendor/github.com/go-fed/activity/streams/util.go

@@ -0,0 +1,66 @@
+package streams
+
+import (
+	"github.com/go-fed/activity/streams/vocab"
+)
+
+const (
+	// jsonLDContext is the key for the JSON-LD specification's context
+	// value. It contains the definitions of the types contained within the
+	// rest of the payload. Important for linked-data representations, but
+	// only applicable to go-fed at code-generation time.
+	jsonLDContext = "@context"
+)
+
+// Serialize adds the context vocabularies contained within the type
+// into the JSON-LD @context field, and aliases them appropriately.
+func Serialize(a vocab.Type) (m map[string]interface{}, e error) {
+	m, e = a.Serialize()
+	if e != nil {
+		return
+	}
+	v := a.JSONLDContext()
+	// Transform the map of vocabulary-to-aliases into a context payload,
+	// but do so in a way that at least keeps it readable for other humans.
+	var contextValue interface{}
+	if len(v) == 1 {
+		for vocab, alias := range v {
+			if len(alias) == 0 {
+				contextValue = vocab
+			} else {
+				contextValue = map[string]string{
+					alias: vocab,
+				}
+			}
+		}
+	} else {
+		var arr []interface{}
+		aliases := make(map[string]string)
+		for vocab, alias := range v {
+			if len(alias) == 0 {
+				arr = append(arr, vocab)
+			} else {
+				aliases[alias] = vocab
+			}
+		}
+		if len(aliases) > 0 {
+			arr = append(arr, aliases)
+		}
+		contextValue = arr
+	}
+	// TODO: Update the context instead if it already exists
+	m[jsonLDContext] = contextValue
+	// TODO: Sort the context based on arbitrary order.
+	// Delete any existing `@context` in child maps.
+	var cleanFnRecur func(map[string]interface{})
+	cleanFnRecur = func(r map[string]interface{}) {
+		for _, v := range r {
+			if n, ok := v.(map[string]interface{}); ok {
+				delete(n, jsonLDContext)
+				cleanFnRecur(n)
+			}
+		}
+	}
+	cleanFnRecur(m)
+	return
+}