Object.get documentation and tests

Author: jmagaram

src/Core__Object.res

@@ -11,7 +11,21 @@
 @variadic @val external assignMany: ({..}, array<{..}>) => {..} = "Object.assign"
 @val external copy: (@as(json`{}`) _, {..}) => {..} = "Object.assign"
 
-@get_index external get: ({..}, string) => option<'a> = ""
+/**
+`get` gets the value of a property by name. Returns `None` if the property does not exist or has the value `undefined`. Otherwise returns `Some`, including if the value is `null`.
+
+## Examples
+
+```rescript
+{"a": 1}->Object.get("a") // Some(1)
+{"a": 1}->Object.get("b") // None
+{"a": undefined}->Object.get("a") // None
+{"a": null}->Object.get("a") // Some(null)
+{"a": 1}->Object.get("toString")->Option.isSome // true
+```
+*/
+@get_index
+external get: ({..}, string) => option<'a> = ""
 @get_index external getSymbol: ({..}, Core__Symbol.t) => option<'a> = ""
 @get_index external getSymbolUnsafe: ({..}, Core__Symbol.t) => 'a = ""
 

test/ObjectTests.mjs

@@ -0,0 +1,119 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Test from "./Test.mjs";
+import * as Curry from "rescript/lib/es6/curry.js";
+import * as Caml_obj from "rescript/lib/es6/caml_obj.js";
+import * as Core__Option from "../src/Core__Option.mjs";
+
+var eq = Caml_obj.equal;
+
+function runGetTest(i) {
+  Test.run([
+        [
+          "ObjectTests.res",
+          15,
+          22,
+          46
+        ],
+        "Object.get: " + i.title + ""
+      ], Curry._1(i.get, Curry._1(i.source, undefined)), eq, i.expected);
+}
+
+runGetTest({
+      title: "prop exists, return Some",
+      source: (function (param) {
+          return {
+                  a: 1
+                };
+        }),
+      get: (function (__x) {
+          return __x["a"];
+        }),
+      expected: 1
+    });
+
+runGetTest({
+      title: "prop NOT exist, return None",
+      source: (function (param) {
+          return {
+                  a: 1
+                };
+        }),
+      get: (function (i) {
+          return i["banana"];
+        }),
+      expected: undefined
+    });
+
+runGetTest({
+      title: "prop like toString, return Some",
+      source: (function (param) {
+          return {
+                  a: 1
+                };
+        }),
+      get: (function (i) {
+          return Core__Option.isSome(i["toString"]);
+        }),
+      expected: true
+    });
+
+runGetTest({
+      title: "prop exist but explicitly undefined, return None",
+      source: (function (param) {
+          return {
+                  a: undefined
+                };
+        }),
+      get: (function (i) {
+          return i["a"];
+        }),
+      expected: undefined
+    });
+
+runGetTest({
+      title: "prop exist but explicitly null, return None",
+      source: (function (param) {
+          return {
+                  a: null
+                };
+        }),
+      get: (function (i) {
+          return i["a"];
+        }),
+      expected: null
+    });
+
+runGetTest({
+      title: "prop exists and is an array, can get it",
+      source: (function (param) {
+          return {
+                  a: [
+                    1,
+                    2,
+                    3
+                  ]
+                };
+        }),
+      get: (function (i) {
+          return Core__Option.getWithDefault(Core__Option.map(i["a"], (function (i) {
+                            return i.concat([
+                                        4,
+                                        5
+                                      ]);
+                          })), []);
+        }),
+      expected: [
+        1,
+        2,
+        3,
+        4,
+        5
+      ]
+    });
+
+export {
+  eq ,
+  runGetTest ,
+}
+/*  Not a pure module */

test/ObjectTests.res

@@ -0,0 +1,65 @@
+open RescriptCore
+
+let eq = (a, b) => a == b
+
+// ===== get =====
+
+type getTestData<'obj, 'res, 'expected> = {
+  title: string,
+  source: unit => 'obj,
+  get: 'obj => 'res,
+  expected: 'expected,
+}
+
+let runGetTest = i =>
+  Test.run(__POS_OF__(`Object.get: ${i.title}`), i.source()->i.get, eq, i.expected)
+
+{
+  title: "prop exists, return Some",
+  source: () => {"a": 1},
+  get: Object.get(_, "a"),
+  expected: Some(1),
+}->runGetTest
+
+{
+  title: "prop NOT exist, return None",
+  source: () => {"a": 1},
+  get: i => i->Object.get("banana"),
+  expected: None,
+}->runGetTest
+
+{
+  title: "prop like toString, return Some",
+  source: () => {"a": 1},
+  get: i => i->Object.get("toString")->Option.isSome,
+  expected: true,
+}->runGetTest
+
+{
+  title: "prop exist but explicitly undefined, return None",
+  source: () => {"a": undefined},
+  get: i => i->Object.get("a"),
+  expected: None,
+}->runGetTest
+
+{
+  title: "prop exist but explicitly null, return None",
+  source: () => {"a": null},
+  get: i => i->Object.get("a"),
+  expected: Some(null),
+}->runGetTest
+
+{
+  title: "prop exists and is an array, can get it",
+  source: () => {"a": [1, 2, 3]},
+  get: i => i->Object.get("a")->Option.map(i => i->Array.concat([4, 5]))->Option.getWithDefault([]),
+  expected: [1, 2, 3, 4, 5],
+}->runGetTest
+
+// This throws an exception
+// {
+//   title: "prop exists but casted wrong on get",
+//   source: () => {"a": 34},
+//   get: i => i->Object.get("a")->Option.map(i => i->Array.concat([4, 5]))->Option.getWithDefault([]),
+//   expected: [],
+// }->runGetTest

test/TestSuite.mjs

@@ -4,6 +4,7 @@ import * as IntTests from "./IntTests.mjs";
 import * as TestTests from "./TestTests.mjs";
 import * as ArrayTests from "./ArrayTests.mjs";
 import * as ErrorTests from "./ErrorTests.mjs";
+import * as ObjectTests from "./ObjectTests.mjs";
 import * as PromiseTest from "./PromiseTest.mjs";
 
 var bign = TestTests.bign;
@@ -26,10 +27,12 @@ var Concurrently = PromiseTest.Concurrently;
 
 var panicTest = ErrorTests.panicTest;
 
-var eq = IntTests.eq;
-
 var $$catch = IntTests.$$catch;
 
+var eq = ObjectTests.eq;
+
+var runGetTest = ObjectTests.runGetTest;
+
 export {
   bign ,
   TestError ,
@@ -41,7 +44,8 @@ export {
   Catching ,
   Concurrently ,
   panicTest ,
-  eq ,
   $$catch ,
+  eq ,
+  runGetTest ,
 }
 /* IntTests Not a pure module */

test/TestSuite.res

@@ -3,3 +3,4 @@ include PromiseTest
 include ErrorTests
 include ArrayTests
 include IntTests
+include ObjectTests