fix: add credentials field to the task schema (#117)

* fix: add `credentials` field to the `task` schema

* fix: add test for the `credentials` field. change to `_asl_payload_template` definition

* test: remove invalid-task-credentials test for primitive types

src/__tests__/definitions/invalid-task-credentials-null.json

@@ -0,0 +1,12 @@
+{
+  "Comment": "https://states-language.net/spec.html#task-state",
+  "StartAt": "X",
+  "States": {
+    "X": {
+      "Type": "Task",
+      "Resource": "arn:aws:swf:us-east-1:123456789012:task:X",
+      "Credentials": null,
+      "End": true
+    }
+  }
+}

src/__tests__/definitions/invalid-task-credentials-object.json

@@ -0,0 +1,16 @@
+{
+  "Comment": "https://states-language.net/spec.html#task-state",
+  "StartAt": "X",
+  "States": {
+    "X": {
+      "Type": "Task",
+      "Resource": "arn:aws:swf:us-east-1:123456789012:task:X",
+      "Credentials": {
+        "flag": true,
+        "expectPath.$": "not a path",
+        "baz": 5
+      },
+      "End": true
+    }
+  }
+}

src/__tests__/definitions/valid-task-credentials.json

@@ -0,0 +1,19 @@
+{
+  "Comment": "https://states-language.net/spec.html#task-state",
+  "StartAt": "X",
+  "States": {
+    "X": {
+      "Type": "Task",
+      "Resource": "arn:aws:swf:us-east-1:123456789012:task:X",
+      "Credentials": {
+        "flag": true,
+        "parts": {
+          "foo.$": "$.vals[0]",
+          "bar.$": "$.vals[3]"
+        },
+        "baz": 5
+      },
+      "End": true
+    }
+  }
+}

src/schemas/task.json

@@ -120,6 +120,9 @@
     },
     "Parameters": {
       "$ref": "paths.json#/definitions/asl_payload_template"
+    },
+    "Credentials": {
+      "$ref": "paths.json#/definitions/asl_payload_template"
     }
   },
   "oneOf": [{