stringStartsWith example

$expected_headers .= "Content-Type: text/plain; charset=UTF-8; format=flowed; delsp=yes$line_end";
    $expected_headers .= "Content-Transfer-Encoding: 8Bit$line_end";
    $expected_headers .= "X-Mailer: Drupal$line_end";
    $expected_headers .= "From: \"Foo, Bar, and Baz\" <from@example.org>$line_end";
    $expected_headers .= "Reply-to: from@example.org$line_end";

    $mailer->expects($this->once())->method('doMail')
      ->with(
        $this->equalTo('to@example.org'),
        $this->equalTo("=?utf-8?Q?test?={$line_end} =?utf-8?Q?subject?="),
        $this->equalTo(''),
        $this->stringStartsWith($expected_headers),
      )
      ->willReturn(TRUE);

    $this->assertTrue($mailer->mail($message));
  }

}

$this->localeProvider->expects(static::once())->method('getLocaleForLanguageId')->willReturn($localeCode);
        $formattedPrice = $this->formatter->formatCurrencyByLanguage(
            $price,
            $currencyISO,
            Uuid::randomHex(),
            $this->createContext($decimalPlaces)
        );

        static::assertThat(
            $formattedPrice,
            static::logicalOr(
                static::stringStartsWith($expectedCurrencySymbol),
                static::stringEndsWith($expectedCurrencySymbol)
            )
        );
    }

    /** * @dataProvider formattingParameterProvider */
    public function testResetWillRemoveExistingFormatters(): void
    {
        $reflector = new \ReflectionClass($this->formatter);