From 38cd1cad3ba6dc5468b17e3f06e647c5514918fc Mon Sep 17 00:00:00 2001
From: Raphael Anyanwu <anyanwuraphaelc@gmail.com>
Date: Mon, 29 Dec 2025 10:54:19 +0100
Subject: [PATCH 1/3] feat: add GetSelectedCountries method to CountryProvider
 class

---
 src/World.Net/CountryProvider.cs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/World.Net/CountryProvider.cs b/src/World.Net/CountryProvider.cs
index b38996a..caef0b0 100644
--- a/src/World.Net/CountryProvider.cs
+++ b/src/World.Net/CountryProvider.cs
@@ -55,4 +55,18 @@ public static ICountry GetCountry(CountryIdentifier countryIdentifier)
 
         throw new CountryNotFoundException($"Country with id {countryIdentifier} was not found.");
     }
+
+    /// <summary>
+    /// Retrieves multiple countries by their unique identifiers.
+    /// </summary>
+    /// <param name="countryIdentifiers">A collection of unique identifiers of the countries to retrieve.</param>
+    /// <returns>
+    /// A collection of <see cref="ICountry"/> instances corresponding to the specified <paramref name="countryIdentifiers"/>.
+    /// </returns>
+    public static IList<ICountry> GetCountries(IEnumerable<CountryIdentifier> countryIdentifiers)
+    {
+        var countries = _countries.Value.Where(x => countryIdentifiers.Contains(x.Key)).Select(x => x.Value);
+
+        return countries.ToList();
+    }
 }

From 19a02ff3a4b11a9da945772b00d573fb2ac68435 Mon Sep 17 00:00:00 2001
From: Raphael Anyanwu <anyanwuraphaelc@gmail.com>
Date: Mon, 29 Dec 2025 10:54:53 +0100
Subject: [PATCH 2/3] add unit tests for selected countries

---
 .../CountryProviderTest.cs                    | 59 ++++++++++++++++++-
 1 file changed, 56 insertions(+), 3 deletions(-)

diff --git a/src/World.Net.UnitTests/CountryProviderTest.cs b/src/World.Net.UnitTests/CountryProviderTest.cs
index be5b089..8c56406 100644
--- a/src/World.Net.UnitTests/CountryProviderTest.cs
+++ b/src/World.Net.UnitTests/CountryProviderTest.cs
@@ -1,6 +1,4 @@
-using World.Net.Helpers;
-
-namespace World.Net.UnitTests;
+namespace World.Net.UnitTests;
 
 public sealed class CountryProviderTest
 {
@@ -57,4 +55,59 @@ public void GetCountry_ShouldThrow_CountryNotFoundException_WhenCountryDoesNotEx
         var exception = Assert.Throws<CountryNotFoundException>(() => CountryProvider.GetCountry(nonExistingCountryId));
         Assert.Equal($"Country with id {nonExistingCountryId} was not found.", exception.Message);
     }
+
+    [Fact]
+    public void GetCountries_ValidIdentifiers_ReturnsCorrectCountries()
+    {
+        // Arrange
+        var indentifiers = new List<CountryIdentifier>
+        {
+            CountryIdentifier.Afghanistan,
+            CountryIdentifier.Brazil
+        };
+
+        // Act
+        var result = CountryProvider.GetCountries(indentifiers);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.NotEmpty(result);
+        Assert.Equal(indentifiers.Count, result.Count);
+    }
+
+    [Fact]
+    public void GetCountries_EmptyIdentifiers_ReturnsEmptyList()
+    {
+        // Arrange
+        var emptyIdentifiers = new List<CountryIdentifier>();
+
+        // Act
+        var result = CountryProvider.GetCountries(emptyIdentifiers);
+
+        // Assert
+        Assert.Empty(result);
+        Assert.Equal(emptyIdentifiers.Count, result.Count);
+    }
+
+    [Fact]
+    public void GetCountries_WhenIdentifiersContainDuplicates_ReturnsDistinctCountries()
+    {
+        // Arrange
+        var indentifiers = new List<CountryIdentifier>
+        {
+            CountryIdentifier.Afghanistan,
+            CountryIdentifier.Afghanistan,
+            CountryIdentifier.Argentina,
+            CountryIdentifier.Brazil,
+            CountryIdentifier.Brazil
+        };
+
+        // Act
+        var result = CountryProvider.GetCountries(indentifiers);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.NotEmpty(result);
+        Assert.Equal(3, result.Count);
+    }
 }
\ No newline at end of file

From 840893d84444453a53220ad86a91882d7d29966b Mon Sep 17 00:00:00 2001
From: Raphael Anyanwu <anyanwuraphaelc@gmail.com>
Date: Mon, 29 Dec 2025 10:55:15 +0100
Subject: [PATCH 3/3] test implementation in program class

---
 src/World.Net.Console/Program.cs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/World.Net.Console/Program.cs b/src/World.Net.Console/Program.cs
index ed5e5e5..f2235f5 100644
--- a/src/World.Net.Console/Program.cs
+++ b/src/World.Net.Console/Program.cs
@@ -21,6 +21,24 @@
     Console.WriteLine($"Error: {ex.Message}");
 }
 
+PrintSeparator("Selected Countries");
+var indentifiers = new List<CountryIdentifier>
+{
+    CountryIdentifier.Afghanistan,
+    CountryIdentifier.Armenia,
+    CountryIdentifier.Niger,
+    CountryIdentifier.Nigeria,
+    CountryIdentifier.Brazil
+};
+
+var selectedCountries = CountryProvider.GetCountries(indentifiers);
+foreach (var country in selectedCountries)
+{
+    Console.WriteLine($"Name: {country.Name,-20} | Capital: {country.Capital}");
+}
+
+Console.WriteLine();
+
 Console.WriteLine();
 Console.WriteLine("Press any key to exit...");
 Console.ReadKey();