[PAN-3067] update the "pantheon blocks export" command usage

pantheon/src/main/java/tech/pegasys/pantheon/cli/subcommands/blocks/BlocksSubCommand.java

@@ -218,7 +218,7 @@ private <T> void importRlpBlocks(final PantheonController<T> controller, final P
    */
   @Command(
       name = "export",
-      description = "This command export a specific block from storage",
+      description = "This command exports a specific block, or list of blocks from storage.",
       mixinStandardHelpOptions = true)
   static class ExportSubCommand implements Runnable {
     @SuppressWarnings("unused")
@@ -228,16 +228,15 @@ static class ExportSubCommand implements Runnable {
     @Option(
         names = "--start-block",
         paramLabel = MANDATORY_LONG_FORMAT_HELP,
-        description = "the starting index of the block list to export (inclusive)",
+        description = "The starting index of the block, or block list to export.",
         arity = "1..1")
     private final Long startBlock = null;
 
     @Option(
         names = "--end-block",
         paramLabel = MANDATORY_LONG_FORMAT_HELP,
         description =
-            "the ending index of the block list to export (exclusive), "
-                + "if not specified a single block will be export",
+            "The ending index of the block list to export (exclusive). If not specified a single block will be exported.",
         arity = "1..1")
     private final Long endBlock = null;
 
@@ -253,7 +252,7 @@ static class ExportSubCommand implements Runnable {
         names = "--to",
         required = true,
         paramLabel = MANDATORY_FILE_FORMAT_HELP,
-        description = "File to write the block list instead of standard output",
+        description = "File to write the block list to.",
         arity = "1..1")
     private File blocksExportFile = null;
 

pantheon/src/test/java/tech/pegasys/pantheon/cli/subcommands/blocks/BlocksSubCommandTest.java

@@ -76,19 +76,19 @@ public class BlocksSubCommandTest extends CommandTestAbstract {
           + System.lineSeparator()
           + "                              --to=<FILE>"
           + System.lineSeparator()
-          + "This command export a specific block from storage"
+          + "This command exports a specific block, or list of blocks from storage."
           + System.lineSeparator()
-          + "      --end-block=<LONG>     the ending index of the block list to export"
+          + "      --end-block=<LONG>     The ending index of the block list to export"
           + System.lineSeparator()
-          + "                               (exclusive), if not specified a single block will be"
+          + "                               (exclusive). If not specified a single block will be"
           + System.lineSeparator()
-          + "                               export"
+          + "                               exported."
           + System.lineSeparator()
-          + "      --start-block=<LONG>   the starting index of the block list to export"
+          + "      --start-block=<LONG>   The starting index of the block, or block list to"
           + System.lineSeparator()
-          + "                               (inclusive)"
+          + "                               export."
           + System.lineSeparator()
-          + "      --to=<FILE>            File to write the block list instead of standard output"
+          + "      --to=<FILE>            File to write the block list to."
           + System.lineSeparator()
           + "  -h, --help                 Show this help message and exit."
           + System.lineSeparator()
@@ -223,7 +223,7 @@ public void blocksExport_noDbDirectory() throws IOException {
     final String expectedErrorOutputStart =
         "Chain is empty.  Unable to export blocks from specified data directory: "
             + folder.getRoot().getAbsolutePath()
-            + "/"
+            + File.separator
             + PantheonController.DATABASE_PATH;
     assertThat(commandOutput.toString()).isEmpty();
     assertThat(commandErrorOutput.toString()).startsWith(expectedErrorOutputStart);
@@ -244,7 +244,7 @@ public void blocksExport_emptyDbDirectory() throws IOException {
     final String expectedErrorOutputStart =
         "Chain is empty.  Unable to export blocks from specified data directory: "
             + folder.getRoot().getAbsolutePath()
-            + "/"
+            + File.separator
             + PantheonController.DATABASE_PATH;
     assertThat(commandOutput.toString()).isEmpty();
     assertThat(commandErrorOutput.toString()).startsWith(expectedErrorOutputStart);