test: find alpha2 by currency

query_test.go

@@ -397,3 +397,40 @@ func TestFindCountryByCallingCode(t *testing.T) {
 		})
 	}
 }
+
+func TestFindCountriesByCurrency(t *testing.T) {
+	tests := []struct {
+		name            string
+		currency        string
+		expectedError   error
+		expectedCountry int
+	}{
+		{
+			name:            "Find countries by valid currency should return countries when currency is present for countries",
+			currency:        "EUR",
+			expectedError:   nil,
+			expectedCountry: 34,
+		},
+		{
+			name:            "Find countries by unknown country code should return error when searching countries",
+			currency:        "ERT",
+			expectedError:   fmt.Errorf("gountries error. Could not find countries with currency name: ERT"),
+			expectedCountry: 0,
+		},
+		{
+			name:            "Find countries by invalid currency length code should return error when searching countries",
+			currency:        "CNYE",
+			expectedError:   fmt.Errorf("gountries error. Invalid currency format: CNYE"),
+			expectedCountry: 0,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			actualCountry, actualError := query.FindCountriesByCurrency(test.currency)
+			if !(reflect.DeepEqual(test.expectedCountry, len(actualCountry)) &&
+				reflect.DeepEqual(test.expectedError, actualError)) {
+				t.Fail()
+			}
+		})
+	}
+}