From e03dce66effc836eb6d81edc100c2cff17f1c33a Mon Sep 17 00:00:00 2001
From: Younies <younies.mahmoud@gmail.com>
Date: Wed, 8 Sep 2021 16:58:23 +0000
Subject: [PATCH] ICU-21730 Port `testGetPreferencesFor` ICU4C tests to ICU4J

See #1850
---
 .../source/test/intltest/units_data_test.cpp  |  1 +
 .../com/ibm/icu/dev/test/impl/UnitsTest.java  | 69 +++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/icu4c/source/test/intltest/units_data_test.cpp b/icu4c/source/test/intltest/units_data_test.cpp
index 304a974a15f..b0ca7e2173e 100644
--- a/icu4c/source/test/intltest/units_data_test.cpp
+++ b/icu4c/source/test/intltest/units_data_test.cpp
@@ -20,6 +20,7 @@ class UnitsDataTest : public IntlTest {
     void runIndexedTest(int32_t index, UBool exec, const char *&name, char *par = NULL) override;
 
     void testGetUnitCategory();
+    // This is a sanity check that only exists in ICU4C.
     void testGetAllConversionRates();
     void testGetPreferencesFor();
 };
diff --git a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/impl/UnitsTest.java b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/impl/UnitsTest.java
index 8c91c7aba89..37679e95bb8 100644
--- a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/impl/UnitsTest.java
+++ b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/impl/UnitsTest.java
@@ -13,6 +13,8 @@ import java.math.MathContext;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.ibm.icu.impl.units.UnitPreferences;
+import com.ibm.icu.impl.units.UnitsData;
 import org.junit.Test;
 
 import com.ibm.icu.dev.test.TestUtil;
@@ -695,4 +697,71 @@ public class UnitsTest {
         }
 
     }
+
+    /**
+     * This test is dependent upon CLDR Data: when the preferences change, the test
+     * may fail: see the constants for expected Max/Min unit identifiers, for US and
+     * World, and for Roads and default lengths.
+     */
+    @Test
+    public void testGetPreferencesFor() {
+        final String USRoadMax = "mile";
+        final String USRoadMin = "foot";
+        final String USLenMax = "mile";
+        final String USLenMin = "inch";
+        final String WorldRoadMax = "kilometer";
+        final String WorldRoadMin = "meter";
+        final String WorldLenMax = "kilometer";
+        final String WorldLenMin = "centimeter";
+        class TestCase {
+            final String name;
+            final String category;
+            final String usage;
+            final String region;
+            final String expectedBiggest;
+            final String expectedSmallest;
+
+            public TestCase(String name, String category, String usage, String region, String expectedBiggest, String expectedSmallest) {
+                this.name = name;
+                this.category = category;
+                this.usage = usage;
+                this.region = region;
+                this.expectedBiggest = expectedBiggest;
+                this.expectedSmallest = expectedSmallest;
+            }
+        }
+
+        TestCase testCases[] = {
+                new TestCase("US road", "length", "road", "US", USRoadMax, USRoadMin),
+                new TestCase("001 road", "length", "road", "001", WorldRoadMax, WorldRoadMin),
+                new TestCase("US lengths", "length", "default", "US", USLenMax, USLenMin),
+                new TestCase("001 lengths", "length", "default", "001", WorldLenMax, WorldLenMin),
+                new TestCase("XX road falls back to 001", "length", "road", "XX", WorldRoadMax, WorldRoadMin),
+                new TestCase("XX default falls back to 001", "length", "default", "XX", WorldLenMax, WorldLenMin),
+                new TestCase("Unknown usage US", "length", "foobar", "US", USLenMax, USLenMin),
+                new TestCase("Unknown usage 001", "length", "foobar", "XX", WorldLenMax, WorldLenMin),
+                new TestCase("Fallback", "length", "person-height-xyzzy", "DE", "centimeter", "centimeter"),
+                new TestCase("Fallback twice", "length", "person-height-xyzzy-foo", "DE", "centimeter",
+                        "centimeter"),
+                // Confirming results for some unitPreferencesTest.txt test cases
+                new TestCase("001 area", "area", "default", "001", "square-kilometer", "square-centimeter"),
+                new TestCase("GB area", "area", "default", "GB", "square-mile", "square-inch"),
+                new TestCase("001 area geograph", "area", "geograph", "001", "square-kilometer", "square-kilometer"),
+                new TestCase("GB area geograph", "area", "geograph", "GB", "square-mile", "square-mile"),
+                new TestCase("CA person-height", "length", "person-height", "CA", "foot-and-inch", "inch"),
+                new TestCase("AT person-height", "length", "person-height", "AT", "meter-and-centimeter",
+                        "meter-and-centimeter"),
+        };
+
+        UnitsData data = new UnitsData();
+        for (TestCase t : testCases) {
+            UnitPreferences.UnitPreference prefs[] = data.getPreferencesFor(t.category, t.usage, t.region);
+            if (prefs.length > 0) {
+                assertEquals(t.name + " - max unit", t.expectedBiggest, prefs[0].getUnit());
+                assertEquals(t.name + " - min unit", t.expectedSmallest, prefs[prefs.length - 1].getUnit());
+            } else {
+                fail(t.name + ": failed to find preferences");
+            }
+        }
+    }
 }
-- 
2.40.0