Add standalone test for ToBooleanBiFunction.

src/test/java/org/apache/commons/lang3/function/ToBooleanBiFunctionTest.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.commons.lang3.function;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests {@link ToBooleanBiFunction}.
+ */
+public class ToBooleanBiFunctionTest {
+
+    @Test
+    public void test() {
+        final ToBooleanBiFunction<String, Integer> func = (t, u) -> Integer.valueOf(t).equals(u);
+        assertTrue(func.applyAsBoolean("1", 1));
+    }
+}