Enhance ledger-tool

Add a command-line argument (min-hashes) to restrict the entries
processed by ledger-tool.  For example, --min-hashes 1 will strip
"empty" Entries, i.e. those with num_hashes = 0.

Add basic ledger tool test

ledger-tool/Cargo.toml

@@ -11,7 +11,12 @@ homepage = "https://solana.com/"
 clap = "2.32.0"
 serde_json = "1.0.34"
 solana = { path = "..", version = "0.12.0" }
+solana-sdk = { path = "../sdk", version = "0.12.0" }
 solana-logger = { path = "../logger", version = "0.12.0" }
 
+[dev-dependencies]
+assert_cmd = "0.10"
+predicates = "1"
+
 [features]
 cuda = []

ledger-tool/src/main.rs

@@ -25,6 +25,14 @@ fn main() {
                 .takes_value(true)
                 .help("Limit to at most the first NUM entries in ledger\n  (only applies to verify, print, json commands)"),
         )
+        .arg(
+            Arg::with_name("min-hashes")
+                .short("h")
+                .long("min-hashes")
+                .value_name("NUM")
+                .takes_value(true)
+                .help("Skip entries with fewer than NUM hashes\n  (only applies to print and json commands)"),
+        )
         .arg(
             Arg::with_name("precheck")
                 .short("p")
@@ -64,6 +72,13 @@ fn main() {
         None => <usize>::max_value(),
     };
 
+    let min_hashes = match matches.value_of("min-hashes") {
+        Some(hashes) => hashes
+            .parse()
+            .expect("please pass a number for --min-hashes"),
+        None => 0,
+    } as u64;
+
     match matches.subcommand() {
         ("print", _) => {
             let entries = match read_ledger(ledger_path, true) {
@@ -78,6 +93,9 @@ fn main() {
                     break;
                 }
                 let entry = entry.unwrap();
+                if entry.num_hashes < min_hashes {
+                    continue;
+                }
                 println!("{:?}", entry);
             }
         }
@@ -88,6 +106,9 @@ fn main() {
                     break;
                 }
                 let entry = entry.unwrap();
+                if entry.num_hashes < min_hashes {
+                    continue;
+                }
                 serde_json::to_writer(stdout(), &entry).expect("serialize");
                 stdout().write_all(b",\n").expect("newline");
             }

ledger-tool/tests/basic.rs

@@ -0,0 +1,57 @@
+use solana::ledger::create_tmp_sample_ledger;
+use solana_sdk::signature::{Keypair, KeypairUtil};
+
+use assert_cmd::prelude::*;
+use std::process::Command;
+use std::process::Output;
+use std::sync::Arc;
+
+fn run_ledger_tool(args: &[&str]) -> Output {
+    Command::main_binary().unwrap().args(args).output().unwrap()
+}
+
+fn count_newlines(chars: &[u8]) -> usize {
+    chars.iter().filter(|&c| *c == '\n' as u8).count()
+}
+
+#[test]
+fn bad_arguments() {
+    // At least a ledger path is required
+    assert!(!run_ledger_tool(&[]).status.success());
+
+    // Invalid ledger path should fail
+    assert!(!run_ledger_tool(&["-l", "invalid_ledger", "verify"])
+        .status
+        .success());
+}
+
+#[test]
+fn nominal() {
+    let keypair = Arc::new(Keypair::new());
+    let (_mint, ledger_path, _genesis_entries) =
+        create_tmp_sample_ledger("test_ledger_tool_nominal", 100, 10, keypair.pubkey(), 50);
+
+    // Basic validation
+    let output = run_ledger_tool(&["-l", &ledger_path, "verify"]);
+    assert!(output.status.success());
+
+    // Print everything
+    let output = run_ledger_tool(&["-l", &ledger_path, "print"]);
+    assert!(output.status.success());
+    assert_eq!(count_newlines(&output.stdout), 13);
+
+    // Only print the first 5 items
+    let output = run_ledger_tool(&["-l", &ledger_path, "-n", "5", "print"]);
+    assert!(output.status.success());
+    assert_eq!(count_newlines(&output.stdout), 5);
+
+    // Skip entries with no hashes (first entry)
+    let output = run_ledger_tool(&["-l", &ledger_path, "-h", "1", "print"]);
+    assert!(output.status.success());
+    assert_eq!(count_newlines(&output.stdout), 12);
+
+    // Skip entries with fewer than 2 hashes (skip everything)
+    let output = run_ledger_tool(&["-l", &ledger_path, "-h", "2", "print"]);
+    assert!(output.status.success());
+    assert_eq!(count_newlines(&output.stdout), 0);
+}