[#390] improve(test): Consistency check in the graviton.conf file (#408)

### What changes were proposed in this pull request?

+ Add ServerConfigTest to keep consistency check in the graviton.conf
file.
+ Use the JAVA reflect method to get all property names from
`ServerConfig.java` and `Configs.java` files.

### Why are the changes needed?

Because property names in the `graviton.conf.template` file need to be
kept consistent with `com/datastrato/graviton/Configs.java` and
`com/datastrato/graviton/server/ServerConfig.java`,
Otherwise, Graviton will not be able to read `graviton.conf` file
correctly.

Fix: #390 

### Does this PR introduce _any_ user-facing change?

N/A

### How was this patch tested?

Added `ServerConfigTest` in the test cases.

conf/graviton.conf.template

@@ -30,7 +30,7 @@ graviton.entity.store = kv
 # The RocksDB entity store
 graviton.entity.store.kv = RocksDBKvBackend
 # The RocksDB backend path for entity store
-graviton.entity.store.kv.rocskdb.path = /tmp/graviton
+graviton.entity.store.kv.rocksdbPath = /tmp/graviton
 
 # THE CONFIGURATION FOR GRAVITON CATALOG
 # The interval in milliseconds to evict the catalog cache

server/build.gradle.kts

@@ -92,3 +92,7 @@ tasks.named("build") {
     throw GradleException("$propertiesFile file not generated!")
   }
 }
+
+tasks.test {
+  environment("GRAVITON_ROOT_DIR", rootDir.path)
+}

server/src/test/java/com/datastrato/graviton/server/TestServerConfig.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2023 Datastrato.
+ * This software is licensed under the Apache License version 2.
+ */
+package com.datastrato.graviton.server;
+
+import com.datastrato.graviton.Configs;
+import com.datastrato.graviton.config.ConfigEntry;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.reflect.Field;
+import java.nio.file.Files;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class TestServerConfig {
+  @Test
+  public void checkGravitonConfFile()
+      throws NoSuchFieldException, IllegalAccessException, IOException {
+    // Load all program config keys from `ServerConfig` and `Configs` into a map
+    Map<String, String> configKeyMap = new HashMap<>();
+    configKeyMap.putAll(getConfigEntryFromClass(ServerConfig.class));
+    configKeyMap.putAll(getConfigEntryFromClass(Configs.class));
+
+    // Load all config keys from `graviton.conf.template` into a map
+    Properties properties = new Properties();
+    String confFile =
+        System.getenv("GRAVITON_ROOT_DIR")
+            + File.separator
+            + "conf"
+            + File.separator
+            + "graviton.conf.template";
+    InputStream in = Files.newInputStream(new File(confFile).toPath());
+    properties.load(in);
+
+    // Check if all config keys from `graviton.conf.template` are defined in `ServerConfig` and
+    // `Configs`
+    for (Map.Entry<Object, Object> entry : properties.entrySet()) {
+      String propKey = (String) entry.getKey();
+      Assertions.assertTrue(
+          configKeyMap.containsKey(propKey),
+          "Config key " + propKey + " is not defined in ConfigEntry");
+    }
+  }
+
+  // Get all ConfigEntry member variables from a config class
+  private Map<String, String> getConfigEntryFromClass(Class<?> configClazz)
+      throws NoSuchFieldException, IllegalAccessException {
+    Map<String, String> configKeyMap = new HashMap<>();
+    // Get all fields
+    Field[] fields = configClazz.getDeclaredFields();
+    for (Field field : fields) {
+      String fieldName = field.getName();
+      Class<?> fieldType = field.getType();
+
+      if (!(fieldType == ConfigEntry.class)) {
+        continue;
+      }
+      Field memberConfigEntry = configClazz.getDeclaredField(fieldName);
+      memberConfigEntry.setAccessible(true);
+
+      // Get all ConfigEntry member variables
+      ConfigEntry<?> configEntry = (ConfigEntry<?>) memberConfigEntry.get(null);
+      String configEntryKey = configEntry.getKey();
+      configKeyMap.put(configEntryKey, fieldName);
+    }
+    return configKeyMap;
+  }
+}