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node_modules/zen-observable/test/constructor.js

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+import assert from 'assert';
+import { testMethodProperty } from './properties.js';
+
+describe('constructor', () => {
+  it('throws if called as a function', () => {
+    assert.throws(() => Observable(() => {}));
+    assert.throws(() => Observable.call({}, () => {}));
+  });
+
+  it('throws if the argument is not callable', () => {
+    assert.throws(() => new Observable({}));
+    assert.throws(() => new Observable());
+    assert.throws(() => new Observable(1));
+    assert.throws(() => new Observable('string'));
+  });
+
+  it('accepts a function argument', () => {
+    let result = new Observable(() => {});
+    assert.ok(result instanceof Observable);
+  });
+
+  it('is the value of Observable.prototype.constructor', () => {
+    testMethodProperty(Observable.prototype, 'constructor', {
+      configurable: true,
+      writable: true,
+      length: 1,
+    });
+  });
+
+  it('does not call the subscriber function', () => {
+    let called = 0;
+    new Observable(() => { called++ });
+    assert.equal(called, 0);
+  });
+
+});