Add sample FormattedResourcesTest using dateTimeConverter substitution

sample/library/build.gradle.kts

@@ -24,4 +24,6 @@ androidComponents {
 
 dependencies {
   testImplementation(libs.icu4j)
+  testImplementation(libs.junit)
+  testImplementation(libs.truth)
 }

sample/library/src/test/kotlin/app/cash/paraphrase/sample/library/FormattedResourcesTest.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2023 Cash App
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package app.cash.paraphrase.sample.library
+
+import androidx.annotation.StringRes
+import com.google.common.truth.Truth.assertThat
+import com.ibm.icu.text.MessageFormat
+import java.time.LocalDate
+import java.time.LocalTime
+import java.time.Month
+import java.util.Locale
+import org.junit.Before
+import org.junit.Test
+
+class FormattedResourcesTest {
+
+  private val stringResolver = FakeStringResolver(
+    R.string.library_date_argument to "{release_date, date, short}",
+    R.string.library_time_argument to "{showtime, time, short}",
+  )
+
+  @Before fun substituteDateTimeConverter() {
+    FormattedResources.dateTimeConverter = JvmDateTimeConverter
+  }
+
+  @Test fun date() {
+    val formattedResource =
+      FormattedResources.library_date_argument(LocalDate.of(2023, Month.NOVEMBER, 3))
+    val result = MessageFormat(stringResolver.getString(formattedResource.id), Locale.US)
+      .format(formattedResource.arguments)
+    assertThat(result).isEqualTo("11/3/23")
+  }
+
+  @Test fun time() {
+    val formattedResource =
+      FormattedResources.library_time_argument(LocalTime.of(14, 37, 21))
+    val result = MessageFormat(stringResolver.getString(formattedResource.id), Locale.US)
+      .format(formattedResource.arguments)
+    assertThat(result).isEqualTo("2:37 PM")
+  }
+
+  private class FakeStringResolver(
+    private val strings: Map<Int, String>,
+  ) {
+
+    constructor(vararg strings: Pair<Int, String>) : this(mapOf(*strings))
+
+    fun getString(@StringRes id: Int): String = strings.getValue(id)
+  }
+}