diff --git a/domain/src/main/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider.kt b/domain/src/main/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider.kt
index 37c034c5e5f..ccecf8cf291 100644
--- a/domain/src/main/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider.kt
+++ b/domain/src/main/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider.kt
@@ -25,7 +25,6 @@ internal class ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider @Inj
     )
   }
 
-  // TODO(#210): Add tests for this classifier.
   override fun matches(answer: StringList, input: StringList): Boolean {
     return answer.htmlList.toSet().intersect(input.htmlList).isNotEmpty()
   }
diff --git a/domain/src/test/java/org/oppia/android/domain/classify/InteractionObjectTestBuilder.kt b/domain/src/test/java/org/oppia/android/domain/classify/InteractionObjectTestBuilder.kt
index dc81d7a0471..804ccb2522e 100644
--- a/domain/src/test/java/org/oppia/android/domain/classify/InteractionObjectTestBuilder.kt
+++ b/domain/src/test/java/org/oppia/android/domain/classify/InteractionObjectTestBuilder.kt
@@ -36,6 +36,10 @@ object InteractionObjectTestBuilder {
     return StringList.newBuilder().addAllHtml(items.toList()).build()
   }
 
+  fun createHtmlStringListInteractionObject(value: StringList): InteractionObject {
+    return InteractionObject.newBuilder().setSetOfHtmlString(value).build()
+  }
+
   fun createWholeNumber(isNegative: Boolean, value: Int): InteractionObject {
     // Whole number fractions imply '0/1' fractional parts.
     return InteractionObject.newBuilder().setFraction(
diff --git a/domain/src/test/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest.kt b/domain/src/test/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest.kt
new file mode 100644
index 00000000000..200d7afd4bf
--- /dev/null
+++ b/domain/src/test/java/org/oppia/android/domain/classify/rules/itemselectioninput/ItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest.kt
@@ -0,0 +1,172 @@
+package org.oppia.android.domain.classify.rules.itemselectioninput
+
+import android.app.Application
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import dagger.BindsInstance
+import dagger.Component
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.oppia.android.domain.classify.InteractionObjectTestBuilder
+import org.robolectric.annotation.Config
+import org.robolectric.annotation.LooperMode
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/** Tests for [ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider]. */
+@RunWith(AndroidJUnit4::class)
+@LooperMode(LooperMode.Mode.PAUSED)
+@Config(manifest = Config.NONE)
+class ItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest {
+
+  private val ITEM_SELECTION_SET_5 =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test1", "test2", "test3", "test4", "test5")
+    )
+
+  private val ITEM_SELECTION_SET_SUBSET =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test1")
+    )
+
+  private val ITEM_SELECTION_SET_ONE_ELEMENT_PRESENT =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test1", "test6")
+    )
+
+  private val ITEM_SELECTION_SET_TWO_ELEMENTS_PRESENT_NO_EXTRA_ELEMENT =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test1", "test2")
+    )
+
+  private val ITEM_SELECTION_SET_TWO_ELEMENTS_PRESENT_WITH_EXTRA_ELEMENT =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test1", "test2", "test6")
+    )
+
+  private val ITEM_SELECTION_SET_EMPTY =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList()
+    )
+
+  private val ITEM_SELECTION_SET_EXCLUSIVE =
+    InteractionObjectTestBuilder.createHtmlStringListInteractionObject(
+      InteractionObjectTestBuilder
+        .createHtmlStringList("test6")
+    )
+
+  @Inject
+  internal lateinit var itemSelectionInputContainsAtLeastOneOfRuleClassifierProvider:
+    ItemSelectionInputContainsAtLeastOneOfRuleClassifierProvider
+
+  private val inputContainsAtLeastOneOfRuleClassifier by lazy {
+    itemSelectionInputContainsAtLeastOneOfRuleClassifierProvider.createRuleClassifier()
+  }
+
+  @Before
+  fun setUp() {
+    setUpTestApplicationComponent()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputIsASubset_answerContainsInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_SUBSET)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isTrue()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputHasOneElementInSet_answerContainsInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_ONE_ELEMENT_PRESENT)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isTrue()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputHasTwoElementsInSetNoneExtra_answerContainsInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_TWO_ELEMENTS_PRESENT_NO_EXTRA_ELEMENT)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isTrue()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputHasTwoElementsInSetOneExtra_answerContainsInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_TWO_ELEMENTS_PRESENT_WITH_EXTRA_ELEMENT)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isTrue()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputIsEmptySet_answerDoesNotContainInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_EMPTY)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isFalse()
+  }
+
+  @Test
+  fun testItemSet_setAnswer_inputIsExclusiveOfSet_answerDoesNotContainInput() {
+    val inputs = mapOf("x" to ITEM_SELECTION_SET_EXCLUSIVE)
+
+    val matches = inputContainsAtLeastOneOfRuleClassifier.matches(
+      answer = ITEM_SELECTION_SET_5,
+      inputs = inputs
+    )
+
+    assertThat(matches).isFalse()
+  }
+
+  private fun setUpTestApplicationComponent() {
+    DaggerItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest_TestApplicationComponent
+      .builder()
+      .setApplication(ApplicationProvider.getApplicationContext())
+      .build()
+      .inject(this)
+  }
+
+  @Singleton
+  @Component(modules = [])
+  interface TestApplicationComponent {
+    @Component.Builder
+    interface Builder {
+      @BindsInstance
+      fun setApplication(application: Application): Builder
+
+      fun build(): TestApplicationComponent
+    }
+
+    fun inject(test: ItemSelectionInputContainsAtLeastOneOfRuleClassifierProviderTest)
+  }
+}