XBRL Unmarshalling (#6)

* proper xml unmarshalling support and validation

* add test for old xbrl

context.go

@@ -64,10 +64,10 @@ type PeriodType string
 
 // All the supported PeriodType values. See Period.Type() for more information.
 const (
-	Duration PeriodType = "duration"
-	Instant  PeriodType = "instant"
-	Forever  PeriodType = "forever"
-	Invalid  PeriodType = "invalid"
+	PeriodTypeDuration PeriodType = "duration"
+	PeriodTypeInstant  PeriodType = "instant"
+	PeriodTypeForever  PeriodType = "forever"
+	PeriodTypeInvalid  PeriodType = "invalid"
 )
 
 // Period contains an instant or interval of time for a Context.
@@ -91,16 +91,16 @@ type Period struct {
 // The comments on the attributes inside the Period struct explain when they can be used depending on what this function returns.
 func (p Period) Type() PeriodType {
 	if p.Forever != nil {
-		return Forever
+		return PeriodTypeForever
 	}
 
 	if p.Instant != nil {
-		return Instant
+		return PeriodTypeInstant
 	}
 
 	if p.StartDate != nil && p.EndDate != nil {
-		return Duration
+		return PeriodTypeDuration
 	}
 
-	return Invalid
+	return PeriodTypeInvalid
 }

context_test.go

@@ -25,7 +25,7 @@ func TestUnmarshalContext(t *testing.T) {
 
 		assert.Equal(t, "http://www.sec.gov/CIK", context.Entity.Identifier.Scheme)
 		assert.Equal(t, "0000320193", context.Entity.Identifier.Value)
-		assert.Equal(t, Instant, context.Period.Type())
+		assert.Equal(t, PeriodTypeInstant, context.Period.Type())
 		assert.Equal(t, "2021-04-16", *context.Period.Instant)
 	})
 
@@ -45,7 +45,7 @@ func TestUnmarshalContext(t *testing.T) {
 
 		assert.Equal(t, "http://www.sec.gov/CIK", context.Entity.Identifier.Scheme)
 		assert.Equal(t, "0000320193", context.Entity.Identifier.Value)
-		assert.Equal(t, Forever, context.Period.Type())
+		assert.Equal(t, PeriodTypeForever, context.Period.Type())
 	})
 
 	t.Run("duration period | has segments", func(t *testing.T) {
@@ -79,7 +79,7 @@ func TestUnmarshalContext(t *testing.T) {
 		assert.Empty(t, context.Entity.Segments[1].Attributes)
 		assert.Equal(t, "I follow my own rules", context.Entity.Segments[1].Value)
 
-		assert.Equal(t, Duration, context.Period.Type())
+		assert.Equal(t, PeriodTypeDuration, context.Period.Type())
 		assert.Equal(t, "2020-09-27", *context.Period.StartDate)
 		assert.Equal(t, "2021-03-27", *context.Period.EndDate)
 	})