Refactor asserts in testing (#227)

testing/asserts.ts

@@ -0,0 +1,179 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { assertEqual as prettyAssertEqual } from "./pretty.ts";
+
+interface Constructor {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  new (...args: any[]): any;
+}
+
+/** Make an assertion, if not `true`, then throw. */
+export function 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.
+ */
+export function equal(actual: unknown, expected: unknown, msg?: string): void {
+  prettyAssertEqual(actual, expected, msg);
+}
+
+/**
+ * Make an assertion that `actual` and `expected` are strictly equal.  If
+ * not then throw.
+ */
+export function assertStrictEq(
+  actual: unknown,
+  expected: unknown,
+  msg?: string
+): 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: ${expectedString}`;
+    }
+    throw new Error(msg);
+  }
+}
+
+/**
+ * Make an assertion that actual contains expected. If not
+ * then thrown.
+ */
+export function assertStrContains(
+  actual: string,
+  expected: string,
+  msg?: string
+): void {
+  if (!actual.includes(expected)) {
+    console.error(
+      "stringContains failed. actual =",
+      actual,
+      "not containing ",
+      expected
+    );
+    if (!msg) {
+      msg = `actual: "${actual}" expected to contains: "${expected}"`;
+    }
+    throw new Error(msg);
+  }
+}
+
+/**
+ * Make an assertion that `actual` match RegExp `expected`. If not
+ * then thrown
+ */
+export function assertMatch(
+  actual: string,
+  expected: RegExp,
+  msg?: string
+): void {
+  if (!expected.test(actual)) {
+    console.error(
+      "stringMatching failed. actual =",
+      actual,
+      "not matching RegExp ",
+      expected
+    );
+    if (!msg) {
+      msg = `actual: "${actual}" expected to match: "${expected}"`;
+    }
+    throw new Error(msg);
+  }
+}
+
+/**
+ * Forcefully throws a failed assertion
+ */
+export function fail(msg?: string): void {
+  // eslint-disable-next-line @typescript-eslint/no-use-before-define
+  assert(false, `Failed assertion${msg ? `: ${msg}` : "."}`);
+}
+
+/** Executes a function, expecting it to throw.  If it does not, then it
+ * throws.  An error class and a string that should be included in the
+ * error message can also be asserted.
+ */
+export function assertThrows(
+  fn: () => void,
+  ErrorClass?: Constructor,
+  msgIncludes = "",
+  msg?: string
+): void {
+  let doesThrow = false;
+  try {
+    fn();
+  } catch (e) {
+    if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
+      msg = `Expected error to be instance of "${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 ? `: ${msg}` : "."}`;
+        throw new Error(msg);
+      }
+    }
+    doesThrow = true;
+  }
+  if (!doesThrow) {
+    msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
+    throw new Error(msg);
+  }
+}
+
+export async function assertThrowsAsync(
+  fn: () => Promise<void>,
+  ErrorClass?: Constructor,
+  msgIncludes = "",
+  msg?: string
+): Promise<void> {
+  let doesThrow = false;
+  try {
+    await fn();
+  } catch (e) {
+    if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
+      msg = `Expected error to be instance of "${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 ? `: ${msg}` : "."}`;
+        throw new Error(msg);
+      }
+    }
+    doesThrow = true;
+  }
+  if (!doesThrow) {
+    msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
+    throw new Error(msg);
+  }
+}

testing/asserts_test.ts

@@ -0,0 +1,46 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { assertStrContains, assertMatch } from "./asserts.ts";
+import { test, assert } from "./mod.ts";
+// import { assertEqual as prettyAssertEqual } from "./pretty.ts";
+// import "./format_test.ts";
+// import "./diff_test.ts";
+// import "./pretty_test.ts";
+
+test(function testingAssertStringContains() {
+  assertStrContains("Denosaurus", "saur");
+  assertStrContains("Denosaurus", "Deno");
+  assertStrContains("Denosaurus", "rus");
+});
+
+test(function testingAssertStringContainsThrow() {
+  let didThrow = false;
+  try {
+    assertStrContains("Denosaurus from Jurassic", "Raptor");
+  } catch (e) {
+    assert(
+      e.message ===
+        `actual: "Denosaurus from Jurassic" expected to contains: "Raptor"`
+    );
+    didThrow = true;
+  }
+  assert(didThrow);
+});
+
+test(function testingAssertStringMatching() {
+  assertMatch("foobar@deno.com", RegExp(/[a-zA-Z]+@[a-zA-Z]+.com/));
+});
+
+test(function testingAssertStringMatchingThrows() {
+  let didThrow = false;
+  try {
+    assertMatch("Denosaurus from Jurassic", RegExp(/Raptor/));
+  } catch (e) {
+    assert(
+      e.message ===
+        `actual: "Denosaurus from Jurassic" expected to match: "/Raptor/"`
+    );
+    didThrow = true;
+  }
+  assert(didThrow);
+});

testing/bench.ts

@@ -1,8 +1,6 @@
 import { bench, runBenchmarks } from "./../benching/mod.ts";
 import { runTests } from "./mod.ts";
 
-import "./test.ts";
-
 bench(async function testingSerial(b) {
   b.start();
   await runTests();

testing/diff.ts

@@ -4,7 +4,11 @@ interface FarthestPoint {
   id: number;
 }
 
-export type DiffType = "removed" | "common" | "added";
+export enum DiffType {
+  removed = "removed",
+  common = "common",
+  added = "added"
+}
 
 export interface DiffResult<T> {
   type: DiffType;
@@ -50,12 +54,12 @@ export default function diff<T>(A: T[], B: T[]): Array<DiffResult<T>> {
   if (!M && !N && !suffixCommon.length && !prefixCommon.length) return [];
   if (!N) {
     return [
-      ...prefixCommon.map(c => ({ type: "common" as DiffType, value: c })),
+      ...prefixCommon.map(c => ({ type: DiffType.common, value: c })),
       ...A.map(a => ({
-        type: (swapped ? "added" : "removed") as DiffType,
+        type: swapped ? DiffType.added : DiffType.removed,
         value: a
       })),
-      ...suffixCommon.map(c => ({ type: "common" as DiffType, value: c }))
+      ...suffixCommon.map(c => ({ type: DiffType.common, value: c }))
     ];
   }
   const offset = N;
@@ -91,18 +95,18 @@ export default function diff<T>(A: T[], B: T[]): Array<DiffResult<T>> {
       const prev = j;
       if (type === REMOVED) {
         result.unshift({
-          type: (swapped ? "removed" : "added") as DiffType,
+          type: swapped ? DiffType.removed : DiffType.added,
           value: B[b]
         });
         b -= 1;
       } else if (type === ADDED) {
         result.unshift({
-          type: (swapped ? "added" : "removed") as DiffType,
+          type: swapped ? DiffType.added : DiffType.removed,
           value: A[a]
         });
         a -= 1;
       } else {
-        result.unshift({ type: "common" as DiffType, value: A[a] });
+        result.unshift({ type: DiffType.common, value: A[a] });
         a -= 1;
         b -= 1;
       }
@@ -194,8 +198,8 @@ export default function diff<T>(A: T[], B: T[]): Array<DiffResult<T>> {
     );
   }
   return [
-    ...prefixCommon.map(c => ({ type: "common" as DiffType, value: c })),
+    ...prefixCommon.map(c => ({ type: DiffType.common, value: c })),
     ...backTrace(A, B, fp[delta + offset], swapped),
-    ...suffixCommon.map(c => ({ type: "common" as DiffType, value: c }))
+    ...suffixCommon.map(c => ({ type: DiffType.common, value: c }))
   ];
 }