Added JSON construction tests

test/constructingJson.nim

@@ -0,0 +1,46 @@
+import "../yaml"
+
+import unittest, json
+
+proc wc(line, column: int, lineContent: string, message: string) =
+    echo "Warning (", line, ",", column, "): ", message, "\n", lineContent
+
+proc ensureEqual(yamlIn, jsonIn: string) =
+    var
+        parser = newYamlParser(initCoreTagLibrary(), wc)
+        yamlResult = constructJson(parser.parse(newStringStream(yamlIn)))
+        jsonResult = parseJson(jsonIn)
+    assert yamlResult.len == 1
+    assert(jsonResult == yamlResult[0])
+
+suite "Constructing JSON":
+    test "Constructing JSON: Simple Sequence":
+        ensureEqual("- 1\n- 2\n- 3", "[1, 2, 3]")
+    
+    test "Constructing JSON: Simple Map":
+        ensureEqual("a: b\nc: d", """{"a": "b", "c": "d"}""")
+    
+    test "Constructing JSON: Complex Structure":
+        ensureEqual("""
+%YAML 1.2
+---
+Foo:
+  - - a
+    - b
+    - c
+  - bla: blubb
+Numbers, bools, special values:
+ - 1
+ - true
+ - ~
+ - 42.23
+ - no
+""", """{
+"Foo": [
+    [ "a", "b", "c"],
+    { "bla": "blubb"}
+],
+"Numbers, bools, special values": [
+    1, true, null, 42.23, false
+]
+}""")