Merge pull request #6 from mojotech/em/fixes

Pin typescript version to avoid prematurely upgrading to 2.7
Disable tslint warning due to bad type inference

Author: mulias

package.json

@@ -85,7 +85,7 @@
     "tslint-config-standard": "^7.0.0",
     "typedoc": "^0.9.0",
     "typedoc-plugin-markdown": "^1.0.12",
-    "typescript": "^2.6.2",
+    "typescript": "~2.6.2",
     "validate-commit-msg": "^2.12.2"
   }
 }

src/decoder.ts

@@ -241,6 +241,7 @@ export class Decoder<A> {
           if (decoders.hasOwnProperty(key)) {
             const r = decoders[key].decode(json[key]);
             if (r.ok === true) {
+              // tslint:disable-next-line:strict-type-predicates
               if (r.result !== undefined) {
                 obj[key] = r.result;
               }

test/json-decode.test.ts

@@ -251,6 +251,16 @@ describe('object', () => {
       result: {a: true, b: 'hats'}
     });
   });
+
+  it('ignores optional fields that decode to undefined', () => {
+    const decoder = object({
+      a: number(),
+      b: optional(string())
+    });
+
+    expect(decoder.run({a: 12, b: 'hats'})).toEqual({ok: true, result: {a: 12, b: 'hats'}});
+    expect(decoder.run({a: 12})).toEqual({ok: true, result: {a: 12}});
+  });
 });
 
 describe('array', () => {

yarn.lock

@@ -3472,9 +3472,9 @@ typescript@2.4.1:
   version "2.4.1"
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.4.1.tgz#c3ccb16ddaa0b2314de031e7e6fee89e5ba346bc"
 
-typescript@^2.6.2:
-  version "2.7.1"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.7.1.tgz#bb3682c2c791ac90e7c6210b26478a8da085c359"
+typescript@~2.6.2:
+  version "2.6.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.6.2.tgz#3c5b6fd7f6de0914269027f03c0946758f7673a4"
 
 uglify-js@^2.6:
   version "2.8.29"