Fix getValue function for legitimate falsy values.

The getValue was failing if the item has a falsy value (false, null, 0, …).
This patch fixes this issue and adds some tests to ensure getValue works as expected.

Author: nchevobbe

packages/devtools-reps/src/object-inspector/tests/object-inspector.js

@@ -816,3 +816,89 @@ describe("getChildren", () => {
     expect(nodePaths).toEqual(childrenPaths);
   });
 });
+
+describe("getValue", () => {
+  it("get the value from contents.value", () => {
+    let item = {
+      contents: {
+        value: "my value"
+      }
+    };
+    expect(getValue(item)).toBe("my value");
+
+    item = {
+      contents: {
+        value: 0
+      }
+    };
+    expect(getValue(item)).toBe(0);
+
+    item = {
+      contents: {
+        value: false
+      }
+    };
+    expect(getValue(item)).toBe(false);
+
+    item = {
+      contents: {
+        value: null
+      }
+    };
+    expect(getValue(item)).toBe(null);
+  });
+
+  it("get the value from contents.getterValue", () => {
+    let item = {
+      contents: {
+        getterValue: "my getter value"
+      }
+    };
+    expect(getValue(item)).toBe("my getter value");
+
+    item = {
+      contents: {
+        getterValue: 0
+      }
+    };
+    expect(getValue(item)).toBe(0);
+
+    item = {
+      contents: {
+        getterValue: false
+      }
+    };
+    expect(getValue(item)).toBe(false);
+
+    item = {
+      contents: {
+        getterValue: null
+      }
+    };
+    expect(getValue(item)).toBe(null);
+  });
+
+  it("get the value from getter and setter", () => {
+    let item = {
+      contents: {
+        get: "get"
+      }
+    };
+    expect(getValue(item)).toEqual({get: "get"});
+
+    item = {
+      contents: {
+        set: "set"
+      }
+    };
+    expect(getValue(item)).toEqual({set: "set"});
+
+    item = {
+      contents: {
+        get: "get",
+        set: "set"
+      }
+    };
+    expect(getValue(item)).toEqual({get: "get", set: "set"});
+  });
+});

packages/devtools-reps/src/object-inspector/utils.js

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 const get = require("lodash/get");
+const has = require("lodash/has");
 const { maybeEscapePropertyName } = require("../reps/rep-utils");
 
 let WINDOW_PROPERTIES = {};
@@ -12,10 +13,13 @@ if (typeof window === "object") {
 }
 
 function getValue(item) {
-  let value = get(item, "contents.value", undefined)
-    || get(item, "contents.getterValue", undefined);
+  let value;
 
-  if (!value && nodeHasAccessors(item)) {
+  if (has(item, "contents.value")) {
+    value = get(item, "contents.value");
+  } else if (has(item, "contents.getterValue")) {
+    value = get(item, "contents.getterValue", undefined);
+  } else if (nodeHasAccessors(item)) {
     value = item.contents;
   }