Make testing more matainable

Original: 2f0ca2242f

testing/mod.ts

@@ -2,123 +2,128 @@
 
 // Do not add imports in this file in order to be compatible with Node.
 
-export function assertEqual(actual: unknown, expected: unknown, msg?: string) {
-  if (!equal(actual, expected)) {
-    let actualString: string;
-    let expectedString: string;
-    try {
-      actualString = String(actual);
-    } catch (e) {
-      actualString = "[Cannot display]";
-    }
-    try {
-      expectedString = String(expected);
-    } catch (e) {
-      expectedString = "[Cannot display]";
-    }
-    console.error(
-      "assertEqual failed. actual =",
-      actualString,
-      "expected =",
-      expectedString
-    );
-    if (!msg) {
-      msg = `actual: ${actualString} expected: ${expectedString}`;
-    }
-    throw new Error(msg);
-  }
-}
-
 interface Constructor {
   new (...args: any[]): any;
 }
 
-interface Assert {
+const assertions = {
-  /** Make an assertion, if not true, then throw. */
+  /** Make an assertion, if not `true`, then throw. */
-  (expr: boolean, msg?: string): void;
+  assert(expr: boolean, msg = ""): void {
+    if (!expr) {
+      throw new Error(msg);
+    }
+  },
 
   /** Make an assertion that `actual` and `expected` are equal, deeply. If not
    * deeply equal, then throw.
    */
-  equal(actual: unknown, expected: unknown, msg?: string): void;
+  equal(actual: unknown, expected: unknown, msg?: string): void {
+    if (!equal(actual, expected)) {
+      let actualString: string;
+      let expectedString: string;
+      try {
+        actualString = String(actual);
+      } catch (e) {
+        actualString = "[Cannot display]";
+      }
+      try {
+        expectedString = String(expected);
+      } catch (e) {
+        expectedString = "[Cannot display]";
+      }
+      console.error(
+        "assertEqual failed. actual =",
+        actualString,
+        "expected =",
+        expectedString
+      );
+      if (!msg) {
+        msg = `actual: ${actualString} expected: ${expectedString}`;
+      }
+      throw new Error(msg);
+    }
+  },
 
   /** Make an assertion that `actual` and `expected` are strictly equal.  If
    * not then throw.
    */
-  strictEqual(actual: unknown, expected: unknown, msg?: string): void;
+  strictEqual(actual: unknown, expected: unknown, msg = ""): void {
+    if (actual !== expected) {
+      let actualString: string;
+      let expectedString: string;
+      try {
+        actualString = String(actual);
+      } catch (e) {
+        actualString = "[Cannot display]";
+      }
+      try {
+        expectedString = String(expected);
+      } catch (e) {
+        expectedString = "[Cannot display]";
+      }
+      console.error(
+        "strictEqual failed. actual =",
+        actualString,
+        "expected =",
+        expectedString
+      );
+      if (!msg) {
+        msg = `actual: ${actualString} expected: ${expectedString}`;
+      }
+      throw new Error(msg);
+    }
+  },
 
   /** Executes a function, expecting it to throw.  If it does not, then it
    * throws.  An error class and a string that should be included in the
    * error message can also be asserted.
    */
-  throws(fn: () => void, errorClass?: Constructor, msgIncludes?: string): void;
+  throws(
-}
+    fn: () => void,
-
+    ErrorClass?: Constructor,
-export const assert = function assert(expr: boolean, msg = "") {
+    msgIncludes = "",
-  if (!expr) {
+    msg = ""
-    throw new Error(msg);
+  ): void {
-  }
+    let doesThrow = false;
-} as Assert;
-
-assert.equal = assertEqual;
-assert.strictEqual = function strictEqual(actual, expected, msg = "") {
-  if (actual !== expected) {
-    let actualString: string;
-    let expectedString: string;
     try {
-      actualString = String(actual);
+      fn();
     } catch (e) {
-      actualString = "[Cannot display]";
+      if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
-    }
+        msg = `Expected error to be instance of "${ErrorClass.name}"${
-    try {
+          msg ? `: ${msg}` : "."
-      expectedString = String(expected);
+        }`;
-    } catch (e) {
-      expectedString = "[Cannot display]";
-    }
-    console.error(
-      "strictEqual failed. actual =",
-      actualString,
-      "expected =",
-      expectedString
-    );
-    if (!msg) {
-      msg = `actual: ${actualString} expected: ${expectedString}`;
-    }
-    throw new Error(msg);
-  }
-};
-assert.throws = function throws(
-  fn,
-  ErrorClass: Constructor,
-  msgIncludes = "",
-  msg = ""
-) {
-  let doesThrow = false;
-  try {
-    fn();
-  } catch (e) {
-    if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
-      msg = `Expected error to be instance of "${ErrorClass.name}"${
-        msg ? `: ${msg}` : "."
-      }`;
-      throw new Error(msg);
-    }
-    if (msgIncludes) {
-      if (!e.message.includes(msgIncludes)) {
-        msg = `Expected error message to include "${msgIncludes}", but got "${
-          e.message
-        }"${msg ? `: ${msg}` : "."}`;
         throw new Error(msg);
       }
+      if (msgIncludes) {
+        if (!e.message.includes(msgIncludes)) {
+          msg = `Expected error message to include "${msgIncludes}", but got "${
+            e.message
+          }"${msg ? `: ${msg}` : "."}`;
+          throw new Error(msg);
+        }
+      }
+      doesThrow = true;
+    }
+    if (!doesThrow) {
+      msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
+      throw new Error(msg);
     }
-    doesThrow = true;
-  }
-  if (!doesThrow) {
-    msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
-    throw new Error(msg);
   }
 };
 
+type Assert = typeof assertions.assert & typeof assertions;
+
+// Decorate assertions.assert with all the assertions
+Object.assign(assertions.assert, assertions);
+
+export const assert = assertions.assert as Assert;
+
+/**
+ * An alias to assert.equal
+ * @deprecated
+ */
+export const assertEqual = assert.equal;
+
 export function equal(c: unknown, d: unknown): boolean {
   const seen = new Map();
   return (function compare(a: unknown, b: unknown) {