Sync with latest jmespath spec updates

Author: jamesls

tests/current.json

@@ -0,0 +1,25 @@
+[
+    {
+        "given": {
+            "foo": [{"name": "a"}, {"name": "b"}],
+            "bar": {"baz": "qux"}
+        },
+        "cases": [
+            {
+                "expression": "@",
+                "result": {
+                    "foo": [{"name": "a"}, {"name": "b"}],
+                    "bar": {"baz": "qux"}
+                }
+            },
+            {
+                "expression": "@.bar",
+                "result": {"baz": "qux"}
+            },
+            {
+                "expression": "@.foo[0]",
+                "result": {"name": "a"}
+            }
+        ]
+    }
+]

tests/slice.json

@@ -127,4 +127,57 @@
       "error": "syntax"
     }
   ]
+}, {
+  "given": {
+    "foo": [{"a": 1}, {"a": 2}, {"a": 3}],
+    "bar": [{"a": {"b": 1}}, {"a": {"b": 2}},
+	    {"a": {"b": 3}}],
+    "baz": 50
+  },
+  "cases": [
+    {
+      "expression": "foo[:2].a",
+      "result": [1, 2]
+    },
+    {
+      "expression": "foo[:2].b",
+      "result": []
+    },
+    {
+      "expression": "foo[:2].a.b",
+      "result": []
+    },
+    {
+      "expression": "bar[::-1].a.b",
+      "result": [3, 2, 1]
+    },
+    {
+      "expression": "bar[:2].a.b",
+      "result": [1, 2]
+    },
+    {
+      "expression": "baz[:2].a",
+      "result": null
+    }
+  ]
+}, {
+  "given": [{"a": 1}, {"a": 2}, {"a": 3}],
+  "cases": [
+    {
+      "expression": "[:]",
+      "result": [{"a": 1}, {"a": 2}, {"a": 3}]
+    },
+    {
+      "expression": "[:2].a",
+      "result": [1, 2]
+    },
+    {
+      "expression": "[::-1].a",
+      "result": [3, 2, 1]
+    },
+    {
+      "expression": "[:2].b",
+      "result": []
+    }
+  ]
 }]

tests/syntax.json

@@ -95,14 +95,6 @@
       {
         "expression": "a][",
         "error": "syntax"
-      },
-      {
-        "expression": "@",
-        "error": "syntax"
-      },
-      {
-        "expression": "@.foo",
-        "error": "syntax"
       }
     ]
   },