Improve optionalsProbability tests; fix

spec/schema/core/option/optionalsProbability.json

 [
   {
     "description": "optionalsProbability option",
+    "schemas": [
+      {
+        "type": "object",
+        "properties": {
+          "optionalProperty1": { "type": "number", "default": 1 },
+          "optionalProperty2": { "type": "number", "default": 1 },
+          "optionalProperty3": { "type": "number", "default": 1 },
+          "optionalProperty4": { "type": "number", "default": 1 },
+          "optionalProperty5": { "type": "number", "default": 1 }
+        }
+      }
+    ],
     "tests": [
       {
         "description": "should handle optionalsProbability option (default = 0) for objects",
-        "schema": {
-          "type": "object",
-          "properties": {
-            "optionalProperty1": { "type": "number", "default": 1 },
-            "optionalProperty2": { "type": "number", "default": 1 },
-            "optionalProperty3": { "type": "number", "default": 1 },
-            "optionalProperty4": { "type": "number", "default": 1 },
-            "optionalProperty5": { "type": "number", "default": 1 }
-          }
-        },
+        "schema": "schemas.0",
         "valid": true,
         "equal": {}
       },
       {
         "description": "should handle optionalsProbability option (= 1) for objects",
-        "schema": {
-          "type": "object",
-          "properties": {
-            "optionalProperty1": { "type": "number", "default": 1 },
-            "optionalProperty2": { "type": "number", "default": 1 },
-            "optionalProperty3": { "type": "number", "default": 1 },
-            "optionalProperty4": { "type": "number", "default": 1 },
-            "optionalProperty5": { "type": "number", "default": 1 }
-          }
-        },
+        "schema": "schemas.0",
         "valid": true,
         "equal": {
           "optionalProperty1": 1,
@@ -56,16 +50,7 @@
       },
       {
         "description": "should handle optionalsProbability option (= 0) overwritten by alwaysFakeOptionals for objects",
-        "schema": {
-          "type": "object",
-          "properties": {
-            "optionalProperty1": { "type": "number", "default": 1 },
-            "optionalProperty2": { "type": "number", "default": 1 },
-            "optionalProperty3": { "type": "number", "default": 1 },
-            "optionalProperty4": { "type": "number", "default": 1 },
-            "optionalProperty5": { "type": "number", "default": 1 }
-          }
-        },
+        "schema": "schemas.0",
         "valid": true,
         "equal": {
           "optionalProperty1": 1,
@@ -90,6 +75,66 @@
         "valid": true,
         "equal": ["a", "a", "a", "a", "a"],
         "require": "core/option/optionalsProbabilityOverwritten"
+      },
+      {
+        "description": "should generate just zero properties if optionalsProbability is 0%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 0,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 0.0
+        }
+      },
+      {
+        "description": "should generate just one property if optionalsProbability is 20%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 1,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 0.2
+        }
+      },
+      {
+        "description": "should generate just two properties if optionalsProbability is 40%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 2,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 0.4
+        }
+      },
+      {
+        "description": "should generate just three properties if optionalsProbability is 60%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 3,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 0.6
+        }
+      },
+      {
+        "description": "should generate just four properties if optionalsProbability is 80%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 4,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 0.8
+        }
+      },
+      {
+        "description": "should generate all properties if optionalsProbability is 100%",
+        "schema": "schemas.0",
+        "valid": true,
+        "count": 5,
+        "set": {
+          "useDefaultValue": true,
+          "optionalsProbability": 1.0
+        }
       }
     ]
   }