feat(std/testing): Add assertExists assertion (denoland#7874)

eugenehp · Oct 26, 2020 · 35caa16 · 35caa16
1 parent ae86cbb
commit 35caa16
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diff --git a/std/testing/asserts.ts b/std/testing/asserts.ts
@@ -329,6 +329,23 @@ export function assertNotStrictEquals(
  );
 }
 
+/**
+ * Make an assertion that actual is not null or undefined. If not
+ * then thrown.
+ */
+export function assertExists(
+ actual: unknown,
+ msg?: string,
+): void {
+ if (actual === undefined || actual === null) {
+ if (!msg) {
+ msg =
+ `actual: "${actual}" expected to match anything but null or undefined`;
+ }
+ throw new AssertionError(msg);
+ }
+}
+
 /**
  * Make an assertion that actual includes expected. If not
  * then thrown.

diff --git a/std/testing/asserts_test.ts b/std/testing/asserts_test.ts
@@ -4,6 +4,7 @@ import {
  assert,
  assertArrayIncludes,
  assertEquals,
+ assertExists,
  AssertionError,
  assertMatch,
  assertNotEquals,
@@ -160,6 +161,34 @@ Deno.test("testingNotEquals", function (): void {
  assertEquals(didThrow, true);
 });
 
+Deno.test("testingAssertExists", function (): void {
+ assertExists("Denosaurus");
+ assertExists(false);
+ assertExists(0);
+ assertExists("");
+ assertExists(-0);
+ assertExists(0);
+ assertExists(NaN);
+ let didThrow;
+ try {
+ assertExists(undefined);
+ didThrow = false;
+ } catch (e) {
+ assert(e instanceof AssertionError);
+ didThrow = true;
+ }
+ assertEquals(didThrow, true);
+ didThrow = false;
+ try {
+ assertExists(null);
+ didThrow = false;
+ } catch (e) {
+ assert(e instanceof AssertionError);
+ didThrow = true;
+ }
+ assertEquals(didThrow, true);
+});
+
 Deno.test("testingAssertStringContains", function (): void {
  assertStringIncludes("Denosaurus", "saur");
  assertStringIncludes("Denosaurus", "Deno");