Error on PoW Skipping for JSON Block Import (#1815)

The JSON block format doesn't include a nonce so we can't skip PoW.

Signed-off-by: Ratan Rai Sur <ratan.r.sur@gmail.com>

CHANGELOG.md

@@ -3,10 +3,11 @@
 ## 21.2.0-RC1
 
 ### 21.2 Breaking Changes
-There are currently no breaking changes in 21.2
+* `--skip-pow-validation-enabled` is now an error with `block import --format JSON`. This is because the JSON format doesn't include the nonce so the proof of work must be calculated.
 
 ### Additions and Improvements
 * Removed unused flags in default genesis configs [\#1812](https://github.com/hyperledger/besu/pull/1812)
+* `--skip-pow-validation-enabled` is now an error with `block import --format JSON`. This is because the JSON format doesn't include the nonce so the proof of work must be calculated. [\#1815](https://github.com/hyperledger/besu/pull/1815)
 
 ### Bug Fixes
 

besu/src/main/java/org/hyperledger/besu/cli/subcommands/blocks/BlocksSubCommand.java

@@ -188,6 +188,10 @@ public class BlocksSubCommand implements Runnable {
       if (blockImportFiles.isEmpty()) {
         throw new ParameterException(spec.commandLine(), "No files specified to import.");
       }
+      if (skipPow && format.equals(BlockImportFormat.JSON)) {
+        throw new ParameterException(
+            spec.commandLine(), "Can't skip proof of work validation for JSON blocks");
+      }
       LOG.info("Import {} block data from {} files", format, blockImportFiles.size());
       final Optional<MetricsService> metricsService = initMetrics(parentCommand);
 

besu/src/test/java/org/hyperledger/besu/cli/subcommands/blocks/BlocksSubCommandTest.java

@@ -145,6 +145,20 @@ public class BlocksSubCommandTest extends CommandTestAbstract {
     assertThat(commandErrorOutput.toString()).startsWith(expectedErrorOutputStart);
   }
 
+  @Test
+  public void callingBlockImportSubCommandWithJSONAndSkipPOWFails() {
+    parseCommand(
+        BLOCK_SUBCOMMAND_NAME,
+        BLOCK_IMPORT_SUBCOMMAND_NAME,
+        "--format",
+        "JSON",
+        "--skip-pow-validation-enabled",
+        "blocks.file");
+    final String expectedErrorOutputStart = "Can't skip";
+    assertThat(commandOutput.toString()).isEmpty();
+    assertThat(commandErrorOutput.toString()).startsWith(expectedErrorOutputStart);
+  }
+
   @Test
   public void callingBlockImportSubCommandHelpMustDisplayUsage() {
     parseCommand(BLOCK_SUBCOMMAND_NAME, BLOCK_IMPORT_SUBCOMMAND_NAME, "--help");