feat: add wrap pipe to add a prefix and a suffix to a string (#117)

* feat: add `wrap` pipe to add a prefix and a suffix to a string

This closes #112

* Update wrap.ts

* Update wrap.ts

spacing

README.md

@@ -40,6 +40,7 @@
     - [match](#match)
     - [lpad](#lpad)
     - [rpad](#rpad)
+    - [wrap](#wrap)
  - [Array](#Array)   
     - [diff](#diff)
     - [flatten](#flatten)
@@ -361,6 +362,17 @@ Right pad a string to a given length using a given pad character  (default is a
 <p>{{'Foo' | rpad: 5: '#'}}</p> <!-- Output: "Foo##" -->
 ```
 
+### wrap
+
+Wrap a string between a prefix and a suffix
+
+
+**Usage:** `string | wrap: prefix: suffix`
+
+```html
+<p>{{'Foo' | wrap: 'nice prefix ': ' and awesome suffix!'}}</p> <!-- Output: "nice prefix Foo and awesome suffix!" -->
+```
+
 ## Array
 
 ### diff

src/pipes/string/index.ts

@@ -50,3 +50,4 @@ export {MatchPipe} from './match';
 export {TestPipe} from './test';
 export {LeftPadPipe} from './lpad';
 export {RightPadPipe} from './rpad';
+export {WrapPipe} from './wrap';

src/pipes/string/wrap.spec.ts

@@ -0,0 +1,37 @@
+import { WrapPipe } from './wrap';
+
+describe('WrapPipe Tests', () => {
+  let pipe: WrapPipe;
+
+  beforeEach(() => {
+    pipe = new WrapPipe();
+  });
+
+  it('Should not do anything if main text is not a string', () => {
+    expect(pipe.transform(null)).toEqual(null);
+    expect(pipe.transform(undefined)).toEqual(undefined);
+    expect(pipe.transform(42 as any)).toEqual(42 as any);
+    expect(pipe.transform({name: 'foo'} as any)).toEqual({name: 'foo'} as any);
+  });
+
+  it('Should skip the prefix if prefix text is not a string', () => {
+    expect(pipe.transform('main text', undefined)).toEqual('main text');
+    expect(pipe.transform('main text', undefined)).toEqual('main text');
+    expect(pipe.transform('main text', 42 as any)).toEqual('main text');
+    expect(pipe.transform('main text', {name: 'foo'} as any)).toEqual('main text');
+  });
+
+  it('Should skip the suffix if suffix text is not a string', () => {
+    expect(pipe.transform('main text', 'great prefix ', undefined)).toEqual('great prefix main text');
+    expect(pipe.transform('main text', 'great prefix ', undefined)).toEqual('great prefix main text');
+    expect(pipe.transform('main text', 'great prefix ', 42 as any)).toEqual('great prefix main text');
+    expect(pipe.transform('main text', 'great prefix ', {name: 'foo'} as any)).toEqual('great prefix main text');
+  });
+
+  it('Should wrap properly', () => {
+    expect(pipe.transform('main text')).toEqual('main text');
+    expect(pipe.transform('main text', 'great prefix ', ' awesome suffix')).toEqual('great prefix main text awesome suffix');
+    expect(pipe.transform('main text', 'only prefix ')).toEqual('only prefix main text');
+    expect(pipe.transform('main text', undefined, ' only suffix')).toEqual('main text only suffix');
+  });
+});

src/pipes/string/wrap.ts

@@ -0,0 +1,15 @@
+import { Pipe, PipeTransform } from '@angular/core';
+import { isString } from '../helpers/helpers';
+
+@Pipe({name: 'wrap'})
+export class WrapPipe implements PipeTransform {
+  transform(str: string, prefix: string = '', suffix: string = ''): string {
+    if (!isString(str)) {
+      return str;
+    }
+
+    return (!!prefix && isString(prefix) ? prefix : '') +
+           str +
+           (!!suffix && isString(suffix) ? suffix : '');
+  }
+}