fix: Improved error message and for properties file missing

hedera-node/hedera-config/src/main/java/com/hedera/node/config/sources/PropertyConfigSource.java

@@ -63,6 +63,10 @@ private static Properties loadProperties(@NonNull final String resourceName) {
         // It is important to use the Thread's context class loader because the resource we want to load might
         // be part of another module.
         try (final var in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resourceName)) {
+            if (in == null) {
+                throw new UncheckedIOException(
+                        "Property file " + resourceName + " could not be found", new IOException());
+            }
             final var props = new Properties();
             props.load(in);
             return props;

hedera-node/hedera-config/src/test/java/com/hedera/node/config/sources/PropertyConfigSourceTest.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2023 Hedera Hashgraph, LLC
+ *
+ * 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 com.hedera.node.config.sources;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.UncheckedIOException;
+import java.lang.reflect.Method;
+import java.util.Properties;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class PropertyConfigSourceTest {
+
+    private Properties properties;
+
+    @BeforeEach
+    void setUp() {
+        properties = new Properties();
+        properties.setProperty("key1", "value1");
+        properties.setProperty("key2", "value2");
+    }
+
+    @Test
+    void testExistentPropertyConfigSource() {
+        // given
+        int ordinal = 1; // used to determine priority of config source
+
+        // when
+        PropertyConfigSource propertyConfigSource = new PropertyConfigSource(properties, ordinal);
+
+        // then
+        assertEquals(2, propertyConfigSource.getPropertyNames().size());
+        assertEquals("value1", propertyConfigSource.getValue("key1"));
+        assertEquals("value2", propertyConfigSource.getValue("key2"));
+        assertEquals(ordinal, propertyConfigSource.getOrdinal());
+    }
+
+    @Test
+    void testPropertyConfigSourceWhenPropertyFileNotFound() {
+        // given
+        String nonExistentFile = "non-existent-file.properties";
+
+        // then
+        assertThrows(UncheckedIOException.class, () -> new PropertyConfigSource(nonExistentFile, 1));
+    }
+
+    @Test
+    void testLoadProperties() throws Exception {
+        // given
+        String existingFile = "bootstrap.properties";
+
+        // when
+        Method method = PropertyConfigSource.class.getDeclaredMethod("loadProperties", String.class);
+        method.setAccessible(true);
+
+        // then
+        // Test successful path
+        Properties properties = (Properties) method.invoke(null, existingFile);
+        assertNotNull(properties);
+    }
+
+    @AfterEach
+    void tearDown() {
+        properties = null;
+    }
+}