Add tests for "value as type" case

tests/valueAsType.js

@@ -0,0 +1,30 @@
+type Type = {
+    a: 'one',
+};
+
+interface Interface {
+    a: 'one';
+}
+
+class Class {
+    a: 'one';
+}
+
+// ###
+({
+    Type: {
+        type: 'record',
+        name: 'Type',
+        fields: [{name: 'a', type: {type: 'enum', symbols: ['one']}}],
+    },
+    Interface: {
+        type: 'record',
+        name: 'Interface',
+        fields: [{name: 'a', type: {type: 'enum', symbols: ['one']}}],
+    },
+    Class: {
+        type: 'record',
+        name: 'Class',
+        fields: [{name: 'a', type: {type: 'enum', symbols: ['one']}}],
+    },
+});