Add test for attribute candidate searching

attributes.go

@@ -80,8 +80,11 @@ func (al *AttributeList) Strings() []string {
 }
 
 func (al *AttributeList) Attribute(identifier AttributeTypeIdentifier) string {
+	if al.CredentialType().Identifier() != identifier.CredentialTypeIdentifier() {
+		return ""
+	}
 	for i, desc := range al.CredentialType().Attributes {
-		if desc.ID == string(identifier.String()) {
+		if desc.ID == string(identifier.Name()) {
 			return al.Strings()[i]
 		}
 	}

irmago_test.go

@@ -199,3 +199,39 @@ func TestAttributeDisjunctionMarshaling(t *testing.T) {
 	disjunction.selected = &disjunction.Attributes[0]
 	require.True(t, disjunction.Satisfied())
 }
+
+func TestCandidates(t *testing.T) {
+	parseMetaStore(t)
+	parseStorage(t)
+	parseAndroidStorage(t)
+
+	attrtype := NewAttributeTypeIdentifier("irma-demo.RU.studentCard.studentID")
+	disjunction := &AttributeDisjunction{
+		Attributes: []AttributeTypeIdentifier{attrtype},
+	}
+	attrs := Manager.Candidates(disjunction)
+	require.NotNil(t, attrs)
+	require.Len(t, attrs, 1)
+
+	attr := attrs[0]
+	require.NotNil(t, attr)
+	require.Equal(t, attr.Type, attrtype)
+
+	disjunction = &AttributeDisjunction{
+		Attributes: []AttributeTypeIdentifier{attrtype},
+		Values:     map[AttributeTypeIdentifier]string{attrtype: "s1234567"},
+	}
+	attrs = Manager.Candidates(disjunction)
+	require.NotNil(t, attrs)
+	require.Len(t, attrs, 1)
+
+	disjunction = &AttributeDisjunction{
+		Attributes: []AttributeTypeIdentifier{attrtype},
+		Values:     map[AttributeTypeIdentifier]string{attrtype: "foobarbaz"},
+	}
+	attrs = Manager.Candidates(disjunction)
+	require.NotNil(t, attrs)
+	require.Empty(t, attrs)
+
+	teardown(t)
+}

manager.go

@@ -201,7 +201,7 @@ func (cm *CredentialManager) Add(cred *Credential) (err error) {
 }
 
 func (cm *CredentialManager) Candidates(disjunction *AttributeDisjunction) []*AttributeIdentifier {
-	candidates := make([]*AttributeIdentifier, 10)
+	candidates := make([]*AttributeIdentifier, 0, 10)
 
 	for _, attribute := range disjunction.Attributes {
 		credId := attribute.CredentialTypeIdentifier()