planning

node_modules/apollo-utilities/src/util/__tests__/warnOnce.ts

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+import { warnOnceInDevelopment } from '../warnOnce';
+
+let lastWarning: string | null;
+let keepEnv: string | undefined;
+let numCalls = 0;
+let oldConsoleWarn: any;
+
+describe('warnOnce', () => {
+  beforeEach(() => {
+    keepEnv = process.env.NODE_ENV;
+    numCalls = 0;
+    lastWarning = null;
+    oldConsoleWarn = console.warn;
+    console.warn = (msg: any) => {
+      numCalls++;
+      lastWarning = msg;
+    };
+  });
+  afterEach(() => {
+    process.env.NODE_ENV = keepEnv;
+    console.warn = oldConsoleWarn;
+  });
+  it('actually warns', () => {
+    process.env.NODE_ENV = 'development';
+    warnOnceInDevelopment('hi');
+    expect(lastWarning).toBe('hi');
+    expect(numCalls).toEqual(1);
+  });
+
+  it('does not warn twice', () => {
+    process.env.NODE_ENV = 'development';
+    warnOnceInDevelopment('ho');
+    warnOnceInDevelopment('ho');
+    expect(lastWarning).toEqual('ho');
+    expect(numCalls).toEqual(1);
+  });
+
+  it('warns two different things once each', () => {
+    process.env.NODE_ENV = 'development';
+    warnOnceInDevelopment('slow');
+    expect(lastWarning).toEqual('slow');
+    warnOnceInDevelopment('mo');
+    expect(lastWarning).toEqual('mo');
+    expect(numCalls).toEqual(2);
+  });
+
+  it('does not warn in production', () => {
+    process.env.NODE_ENV = 'production';
+    warnOnceInDevelopment('lo');
+    warnOnceInDevelopment('lo');
+    expect(numCalls).toEqual(0);
+  });
+
+  it('warns many times in test', () => {
+    process.env.NODE_ENV = 'test';
+    warnOnceInDevelopment('yo');
+    warnOnceInDevelopment('yo');
+    expect(lastWarning).toEqual('yo');
+    expect(numCalls).toEqual(2);
+  });
+});