Add unit tests for the logger

README.md

@@ -89,7 +89,7 @@ On the CLI, the header argument can be repeated. Format is "Name: value".
 
 #### `--quiet`, `logger`
 In CLI, the quiet flag will disable all output except errors.
-Using the API, you can provide a logger config, which is either `null` to disable logging  completely, a function taking any number of arguments, or an object with two members, `log` and `error`, each being a function taking any number of arguments.
+Using the API, you can provide a logger config, which is either `null` to disable logging completely, a function taking any number of arguments, or an object with two members, `log` and `error`, each being a function taking any number of arguments.
 
 * Default: `false` in CLI, `console` in API
 

src/Config.ts

@@ -13,5 +13,5 @@ export interface IConfig {
     mergedSegmentsFile?: string;
     outputFile: string;
     httpHeaders?: HttpHeaders;
-    logger?: ILogger | ((...params: any) => void);
+    logger?: ILogger | ((...params: any) => void) | null;
 }

test/Logger.spec.ts

@@ -0,0 +1,31 @@
+import { buildLogger } from "../src/Logger";
+
+describe("buildLogger", () => {
+    it("Should use the console by default", ()  => {
+        expect(buildLogger(undefined)).toBe(console);
+    });
+
+    it("Should return a no-op logger when passed null", ()  => {
+        const logger = buildLogger(null);
+
+        expect(typeof logger.error).toBe("function");
+        expect(typeof logger.log).toBe("function");
+        expect(logger.error).toBe(logger.log);
+    });
+
+    it("Should provide a logger object when passed a function", () => {
+        const input = (): void => { /* no-op */ };
+        const logger = buildLogger(input);
+
+        expect(logger.error).toBe(input);
+        expect(logger.log).toBe(input);
+    })
+
+    it("Should use the passed logged when provided", () => {
+        const input = {
+            error(): void { /* no-op */ },
+            log(): void { /* no-op */ },
+        };
+        expect(buildLogger(input)).toBe(input);
+    })
+});