diff --git a/tools/aconfig/tests/AconfigHostTest.java b/tools/aconfig/tests/AconfigHostTest.java
new file mode 100644
index 0000000..29a01e3
--- /dev/null
+++ b/tools/aconfig/tests/AconfigHostTest.java
@@ -0,0 +1,88 @@
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+
+import com.android.aconfig.test.FakeFeatureFlagsImpl;
+import com.android.aconfig.test.FeatureFlags;
+import com.android.aconfig.test.FeatureFlagsImpl;
+import com.android.aconfig.test.Flags;
+
+@RunWith(JUnit4.class)
+public final class AconfigHostTest {
+    @Test
+    public void testThrowsExceptionIfFlagNotSet() {
+        assertThrows(NullPointerException.class, () -> Flags.disabledRo());
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        assertThrows(IllegalArgumentException.class, () -> featureFlags.disabledRo());
+    }
+
+    @Test
+    public void testSetFlagInFakeFeatureFlagsImpl() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertTrue(featureFlags.enabledRw());
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, false);
+        assertFalse(featureFlags.enabledRw());
+
+        //Set Flags
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertTrue(Flags.enabledRw());
+        Flags.unsetFeatureFlags();
+    }
+
+    @Test
+    public void testSetFlagWithRandomName() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        assertThrows(IllegalArgumentException.class,
+            () -> featureFlags.setFlag("Randome_name", true));
+    }
+
+    @Test
+    public void testResetFlagsInFakeFeatureFlagsImpl() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RO, true);
+        assertTrue(featureFlags.enabledRo());
+        featureFlags.resetAll();
+        assertThrows(IllegalArgumentException.class, () -> featureFlags.enabledRo());
+
+        // Set value after reset
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RO, false);
+        assertFalse(featureFlags.enabledRo());
+    }
+
+    @Test
+    public void testFlagsSetFeatureFlags() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        assertTrue(Flags.enabledRw());
+        Flags.unsetFeatureFlags();
+    }
+
+    @Test
+    public void testFlagsUnsetFeatureFlags() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        assertTrue(Flags.enabledRw());
+
+        Flags.unsetFeatureFlags();
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+    }
+
+    @Test
+    public void testFeatureFlagsImplNotImpl() {
+        FeatureFlags featureFlags = new FeatureFlagsImpl();
+        assertThrows(UnsupportedOperationException.class,
+            () -> featureFlags.enabledRw());
+    }
+}