feat(assertions): 'not' matcher (#16240)

Supply a 'not' matcher that can be used to invert the matching pattern

relates #15868

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: Niranjan Jayakar

packages/@aws-cdk/assertions/README.md

@@ -238,6 +238,35 @@ target array. Out of order will be recorded as a match failure.
 Alternatively, the `Match.arrayEquals()` API can be used to assert that the target is
 exactly equal to the pattern array.
 
+### Not Matcher
+
+The not matcher inverts the search pattern and matches all patterns in the path that does
+not match the pattern specified.
+
+```ts
+// Given a template -
+// {
+//   "Resources": {
+//     "MyBar": {
+//       "Type": "Foo::Bar",
+//       "Properties": {
+//         "Fred": ["Flob", "Cat"]
+//       }
+//     }
+//   }
+// }
+
+// The following will NOT throw an assertion error
+assert.hasResourceProperties('Foo::Bar', {
+  Fred: Match.not(['Flob']),
+});
+
+// The following will throw an assertion error
+assert.hasResourceProperties('Foo::Bar', Match.objectLike({
+  Fred: Match.not(['Flob', 'Cat']);
+}});
+```
+
 ## Strongly typed languages
 
 Some of the APIs documented above, such as `templateMatches()` and

packages/@aws-cdk/assertions/lib/match.ts

@@ -55,6 +55,14 @@ export abstract class Match {
   public static objectEquals(pattern: {[key: string]: any}): Matcher {
     return new ObjectMatch('objectEquals', pattern, { partial: false });
   }
+
+  /**
+   * Matches any target which does NOT follow the specified pattern.
+   * @param pattern the pattern to NOT match
+   */
+  public static not(pattern: any): Matcher {
+    return new NotMatch('not', pattern);
+  }
 }
 
 /**
@@ -82,7 +90,6 @@ class LiteralMatch extends Matcher {
 
     super();
     this.partialObjects = options.partialObjects ?? false;
-    this.name = 'exact';
 
     if (Matcher.isMatcher(this.pattern)) {
       throw new Error('LiteralMatch cannot directly contain another matcher. ' +
@@ -143,11 +150,6 @@ class ArrayMatch extends Matcher {
 
     super();
     this.partial = options.subsequence ?? true;
-    if (this.partial) {
-      this.name = 'arrayWith';
-    } else {
-      this.name = 'arrayEquals';
-    }
   }
 
   public test(actual: any): MatchResult {
@@ -211,11 +213,6 @@ class ObjectMatch extends Matcher {
 
     super();
     this.partial = options.partial ?? true;
-    if (this.partial) {
-      this.name = 'objectLike';
-    } else {
-      this.name = 'objectEquals';
-    }
   }
 
   public test(actual: any): MatchResult {
@@ -254,6 +251,26 @@ class ObjectMatch extends Matcher {
   }
 }
 
+class NotMatch extends Matcher {
+  constructor(
+    public readonly name: string,
+    private readonly pattern: {[key: string]: any}) {
+
+    super();
+  }
+
+  public test(actual: any): MatchResult {
+    const matcher = Matcher.isMatcher(this.pattern) ? this.pattern : new LiteralMatch(this.name, this.pattern);
+
+    const innerResult = matcher.test(actual);
+    const result = new MatchResult(actual);
+    if (innerResult.failCount === 0) {
+      result.push(this, [], `Found unexpected match: ${JSON.stringify(actual, undefined, 2)}`);
+    }
+    return result;
+  }
+}
+
 function getType(obj: any): string {
   return Array.isArray(obj) ? 'array' : typeof obj;
 }

packages/@aws-cdk/assertions/test/match.test.ts

@@ -194,17 +194,112 @@ describe('Matchers', () => {
       expectFailure(matcher, { foo: 'bar', baz: 'qux' }, [/Unexpected key at \/baz/]);
     });
   });
+
+  describe('not()', () => {
+    let matcher: Matcher;
+
+    test('literal', () => {
+      matcher = Match.not('foo');
+      expectPass(matcher, 'bar');
+      expectPass(matcher, 3);
+
+      expectFailure(matcher, 'foo', ['Found unexpected match: "foo"']);
+    });
+
+    test('object', () => {
+      matcher = Match.not({ foo: 'bar' });
+      expectPass(matcher, 'bar');
+      expectPass(matcher, 3);
+      expectPass(matcher, { foo: 'baz' });
+      expectPass(matcher, { bar: 'foo' });
+
+      const msg = [
+        'Found unexpected match: {',
+        '  "foo": "bar"',
+        '}',
+      ].join('\n');
+      expectFailure(matcher, { foo: 'bar' }, [msg]);
+    });
+
+    test('array', () => {
+      matcher = Match.not(['foo', 'bar']);
+      expectPass(matcher, 'foo');
+      expectPass(matcher, []);
+      expectPass(matcher, ['bar']);
+      expectPass(matcher, ['foo', 3]);
+
+      const msg = [
+        'Found unexpected match: [',
+        '  "foo",',
+        '  "bar"',
+        ']',
+      ].join('\n');
+      expectFailure(matcher, ['foo', 'bar'], [msg]);
+    });
+
+    test('as a nested matcher', () => {
+      matcher = Match.exact({
+        foo: { bar: Match.not([1, 2]) },
+      });
+
+      expectPass(matcher, {
+        foo: { bar: [1] },
+      });
+      expectPass(matcher, {
+        foo: { bar: ['baz'] },
+      });
+
+      const msg = [
+        'Found unexpected match: [',
+        '  1,',
+        '  2',
+        '] at /foo/bar',
+      ].join('\n');
+      expectFailure(matcher, {
+        foo: { bar: [1, 2] },
+      }, [msg]);
+    });
+
+    test('with nested matcher', () => {
+      matcher = Match.not({
+        foo: { bar: Match.arrayWith([1]) },
+      });
+
+      expectPass(matcher, {
+        foo: { bar: [2] },
+      });
+      expectPass(matcher, 'foo');
+
+      const msg = [
+        'Found unexpected match: {',
+        '  "foo": {',
+        '    "bar": [',
+        '      1,',
+        '      2',
+        '    ]',
+        '  }',
+        '}',
+      ].join('\n');
+      expectFailure(matcher, {
+        foo: { bar: [1, 2] },
+      }, [msg]);
+    });
+  });
 });
 
 function expectPass(matcher: Matcher, target: any): void {
   expect(matcher.test(target).hasFailed()).toEqual(false);
 }
 
-function expectFailure(matcher: Matcher, target: any, expected: (string | RegExp)[]): void {
-  const actual = matcher.test(target).toHumanStrings();
+function expectFailure(matcher: Matcher, target: any, expected: (string | RegExp)[] = []): void {
+  const result = matcher.test(target);
+  expect(result.failCount).toBeGreaterThan(0);
+  const actual = result.toHumanStrings();
+  if (expected.length > 0) {
+    expect(actual.length).toEqual(expected.length);
+  }
   for (let i = 0; i < expected.length; i++) {
     const e = expected[i];
     expect(actual[i]).toMatch(e);
   }
-  expect(expected.length).toEqual(actual.length);
 }