fix: the countries statistics on a collection page doesn't count the series with the non-specified countries.

As countries are unknown, let's follow the pessimistic scenario and assume that  all the series
belong to the same country.

Fix #371

Author: php-coder

src/main/resources/sql/country_dao_queries.properties

@@ -39,11 +39,11 @@ SELECT COUNT(*) \
  WHERE LOWER(name_ru) = :name
 
 country.count_countries_of_collection = \
-SELECT COUNT(DISTINCT s.country_id) AS counter \
-  FROM collections_series cs \
-  JOIN series s \
-    ON s.id = cs.series_id \
- WHERE cs.collection_id = :collection_id
+   SELECT COUNT(DISTINCT COALESCE(s.country_id, -1)) AS counter \
+     FROM collections_series cs \
+LEFT JOIN series s \
+       ON s.id = cs.series_id \
+    WHERE cs.collection_id = :collection_id
 
 country.count_countries_added_since = \
 SELECT COUNT(*) \

src/test/java/ru/mystamps/web/feature/country/JdbcCountryDaoTest.java

@@ -88,6 +88,32 @@ public void countCountriesOfCollectionWithMultipleSeriesFromEachCountry() {
 		assertThat(numberOfCountries).isEqualTo(2);
 	}
 
+	@Test
+	@Sql(
+		scripts = {
+			"/db/users-coder.sql",
+			"/db/collections-coder.sql",
+			"/db/categories-sport.sql",
+			"/db/series-2-sport-qty3.sql",
+			"/db/series-3-sport-qty7.sql"
+		},
+		statements =  {
+			"INSERT INTO collections_series(collection_id, series_id, number_of_stamps) "
+				+ "VALUES (1, 2, 3), (1, 3, 7)"
+		}
+	)
+	public void countCountriesOfCollectionWithSeriesFromUnknownCountries() {
+		// as countries are unknown, we assume the pessimistic scenario
+		// where all the series belong to the same country
+		
+		// given
+		long expectedNumberOfCountries = 1;
+		// when
+		long numberOfCountries = countryDao.countCountriesOfCollection(1);
+		// then
+		assertThat(numberOfCountries).isEqualTo(expectedNumberOfCountries);
+	}
+	
 	//
 	// Tests for getStatisticsOf()
 	//