discover_by_testing_failed_test.kt

    @Test fun `the configuration is not valid when its header is empty`() {
        whenever(mockStorage.get(KEY_AGENT)).thenReturn("an agent")
        whenever(mockStorage.get(KEY_VERSION)).thenReturn("a version")
        whenever(mockStorage.get(KEY_HEADER)).thenReturn("")

        val actual = configuration().isValid

        assertFalse(actual)
    }