added ability to revert (#21)

tests/unit/application/State/Code/ApplicationCode.spec.ts

@@ -0,0 +1,65 @@
+import { CategoryStub } from './../../../stubs/CategoryStub';
+import { ScriptStub } from './../../../stubs/ScriptStub';
+import { ApplicationStub } from './../../../stubs/ApplicationStub';
+import { UserSelection } from '@/application/State/Selection/UserSelection';
+import { ApplicationCode } from '@/application/State/Code/ApplicationCode';
+import 'mocha';
+import { expect } from 'chai';
+import { SelectedScript } from '@/application/State/Selection/SelectedScript';
+
+describe('ApplicationCode', () => {
+    describe('ctor', () => {
+        it('empty when selection is empty', () => {
+            // arrange
+            const selection = new UserSelection(new ApplicationStub(), []);
+            const sut = new ApplicationCode(selection, 'version');
+            // act
+            const actual = sut.current;
+            // assert
+            expect(actual).to.have.lengthOf(0);
+        });
+        it('has code when selection is not empty', () => {
+            // arrange
+            const scripts = [new ScriptStub('first'), new ScriptStub('second')];
+            const app = new ApplicationStub().withAction(new CategoryStub(1).withScripts(...scripts));
+            const selection = new UserSelection(app, scripts);
+            const version = 'version-string';
+            const sut = new ApplicationCode(selection, version);
+            // act
+            const actual = sut.current;
+            // assert
+            expect(actual).to.have.length.greaterThan(0).and.include(version);
+        });
+    });
+    describe('user selection changes', () => {
+        it('empty when selection is empty', () => {
+            // arrange
+            let signaled: string;
+            const scripts = [new ScriptStub('first'), new ScriptStub('second')];
+            const app = new ApplicationStub().withAction(new CategoryStub(1).withScripts(...scripts));
+            const selection = new UserSelection(app, scripts);
+            const sut = new ApplicationCode(selection, 'version');
+            sut.changed.on((code) => signaled = code);
+            // act
+            selection.changed.notify([]);
+            // assert
+            expect(signaled).to.have.lengthOf(0);
+            expect(signaled).to.equal(sut.current);
+        });
+        it('has code when selection is not empty', () => {
+            // arrange
+            let signaled: string;
+            const scripts = [new ScriptStub('first'), new ScriptStub('second')];
+            const app = new ApplicationStub().withAction(new CategoryStub(1).withScripts(...scripts));
+            const selection = new UserSelection(app, scripts);
+            const version = 'version-string';
+            const sut = new ApplicationCode(selection, version);
+            sut.changed.on((code) => signaled = code);
+            // act
+            selection.changed.notify(scripts.map((s) => new SelectedScript(s, false)));
+            // assert
+            expect(signaled).to.have.length.greaterThan(0).and.include(version);
+            expect(signaled).to.equal(sut.current);
+        });
+    });
+});