for simple read jons test

lib/file/file_test.go

@@ -135,6 +135,19 @@ func TestLoadModule_File(t *testing.T) {
 				assert.eq(l2, [text])
 			`),
 		},
+		{
+			name: `read json`,
+			script: itn.HereDoc(`
+				load('file', 'read_json')
+				j1 = read_json('testdata/json1.json')
+				assert.true(type(j1) == "dict")
+				assert.eq(j1["num"], 42)
+				assert.eq(j1["undef"], None)
+				assert.eq(j1["bool"], True)
+				assert.eq(j1["arr"], [1,2,3])
+				assert.eq(j1["obj"], {"foo": "bar", "baz": "qux"})
+			`),
+		},
 		{
 			name: `write no args`,
 			script: itn.HereDoc(`

lib/file/testdata/.gitattributes

@@ -1 +1,2 @@
 *.txt binary
+*.json binary

lib/file/testdata/json1.json

@@ -0,0 +1,11 @@
+{
+  "num": 42,
+    "str": "hello",
+    "bool": true,
+    "arr": [1, 2, 3],
+    "obj": {
+    "foo": "bar",
+        "baz": "qux"
+    },
+  "undef": null
+}