diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/README.md b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/README.md
new file mode 100644
index 0000000..e69de29
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleArrayDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleArrayDefinition.st
new file mode 100644
index 0000000..48c6ccf
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleArrayDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleArrayDefinition
+	| definition schema string |
+	string := '{"type":"array"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaArray.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleBooleanDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleBooleanDefinition.st
new file mode 100644
index 0000000..76d8034
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleBooleanDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleBooleanDefinition
+	| definition schema string |
+	string := '{"type":"boolean"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaBoolean.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleIntegerDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleIntegerDefinition.st
new file mode 100644
index 0000000..3fe4699
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleIntegerDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleIntegerDefinition
+	| definition schema string |
+	string := '{"type":"integer"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaInteger.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNullDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNullDefinition.st
new file mode 100644
index 0000000..015d3c8
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNullDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleNullDefinition
+	| definition schema string |
+	string := '{"type":"null"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaNull.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNumberDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNumberDefinition.st
new file mode 100644
index 0000000..6ff7824
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleNumberDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleNumberDefinition
+	| definition schema string |
+	string := '{"type":"number"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaNumber.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleObjectDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleObjectDefinition.st
new file mode 100644
index 0000000..3f8d7a2
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleObjectDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleObjectDefinition
+	| definition schema string |
+	string := '{"type":"object"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaObject.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleStringDefinition.st b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleStringDefinition.st
new file mode 100644
index 0000000..0e6e39d
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/instance/testSimpleStringDefinition.st
@@ -0,0 +1,8 @@
+tests
+testSimpleStringDefinition
+	| definition schema string |
+	string := '{"type":"string"}'.
+	definition := JSONSchemaDefinition fromString: string.
+	schema := definition schema.
+	self assert: schema class equals: JSONSchemaString.
+	self assert: schema jsonString equals: string
\ No newline at end of file
diff --git a/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/properties.json b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/properties.json
new file mode 100644
index 0000000..beb77a2
--- /dev/null
+++ b/source/JSONSchema-Core-Tests.package/JSONSchemaDefinitionTests.class/properties.json
@@ -0,0 +1,11 @@
+{
+	"commentStamp" : "",
+	"super" : "TestCase",
+	"category" : "JSONSchema-Core-Tests",
+	"classinstvars" : [ ],
+	"pools" : [ ],
+	"classvars" : [ ],
+	"instvars" : [ ],
+	"name" : "JSONSchemaDefinitionTests",
+	"type" : "normal"
+}
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONSchema.class/instance/jsonString.st b/source/JSONSchema-Core.package/JSONSchema.class/instance/jsonString.st
new file mode 100644
index 0000000..d9579dd
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONSchema.class/instance/jsonString.st
@@ -0,0 +1,3 @@
+conversion
+jsonString
+	^ NeoJSONWriter toString: self
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONSchemaNull.class/README.md b/source/JSONSchema-Core.package/JSONSchemaNull.class/README.md
new file mode 100644
index 0000000..e69de29
diff --git a/source/JSONSchema-Core.package/JSONSchemaNull.class/class/typeName.st b/source/JSONSchema-Core.package/JSONSchemaNull.class/class/typeName.st
new file mode 100644
index 0000000..435dce7
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONSchemaNull.class/class/typeName.st
@@ -0,0 +1,3 @@
+instance creation
+typeName
+	^ 'null'
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONSchemaNull.class/properties.json b/source/JSONSchema-Core.package/JSONSchemaNull.class/properties.json
new file mode 100644
index 0000000..b03f501
--- /dev/null
+++ b/source/JSONSchema-Core.package/JSONSchemaNull.class/properties.json
@@ -0,0 +1,11 @@
+{
+	"commentStamp" : "",
+	"super" : "JSONPrimitiveSchema",
+	"category" : "JSONSchema-Core-Model",
+	"classinstvars" : [ ],
+	"pools" : [ ],
+	"classvars" : [ ],
+	"instvars" : [ ],
+	"name" : "JSONSchemaNull",
+	"type" : "normal"
+}
\ No newline at end of file
diff --git a/source/JSONSchema-Core.package/JSONSchemaObject.class/instance/properties.st b/source/JSONSchema-Core.package/JSONSchemaObject.class/instance/properties.st
index d0d3a11..820e779 100644
--- a/source/JSONSchema-Core.package/JSONSchemaObject.class/instance/properties.st
+++ b/source/JSONSchema-Core.package/JSONSchemaObject.class/instance/properties.st
@@ -1,4 +1,4 @@
 accessing
 properties 
-	^ properties ifNil: [ 
-		properties := Dictionary new ]
\ No newline at end of file
+	^ properties "ifNil: [ 
+		properties := Dictionary new ]"
\ No newline at end of file