Merge pull request #1631 from jqnatividad/1630-enum_start_option

`enum`: add `--start` option

src/cmd/enumerate.rs

@@ -28,6 +28,8 @@ Usage:
 enum options:
     -c, --new-column <name>  Name of the column to create.
                              Will default to "index".
+    --start <value>          The value to start the enumeration from.
+                             (default: 0)
     --constant <value>       Fill a new column with the given value.
                              Changes the default column name to "constant".
                              To specify a null value, pass the literal "<NULL>".
@@ -61,6 +63,7 @@ const NULL_VALUE: &str = "<NULL>";
 struct Args {
     arg_input:       Option<String>,
     flag_new_column: Option<String>,
+    flag_start:      u64,
     flag_constant:   Option<String>,
     flag_copy:       Option<SelectColumns>,
     flag_uuid:       bool,
@@ -111,7 +114,7 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
     }
 
     let mut record = csv::ByteRecord::new();
-    let mut counter: u64 = 0;
+    let mut counter: u64 = args.flag_start;
 
     while rdr.read_byte_record(&mut record)? {
         if let Some(constant_value) = &args.flag_constant {

tests/test_enumerate.rs

@@ -27,6 +27,33 @@ fn enumerate() {
     assert_eq!(got, expected);
 }
 
+#[test]
+fn enumerate_counter() {
+    let wrk = Workdir::new("enumerate_counter");
+    wrk.create(
+        "data.csv",
+        vec![
+            svec!["letter", "number"],
+            svec!["a", "13"],
+            svec!["b", "24"],
+            svec!["c", "72"],
+            svec!["d", "7"],
+        ],
+    );
+    let mut cmd = wrk.command("enum");
+    cmd.args(&["--start", "10"]).arg("data.csv");
+
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = vec![
+        svec!["letter", "number", "index"],
+        svec!["a", "13", "10"],
+        svec!["b", "24", "11"],
+        svec!["c", "72", "12"],
+        svec!["d", "7", "13"],
+    ];
+    assert_eq!(got, expected);
+}
+
 #[test]
 fn enumerate_column_name() {
     let wrk = Workdir::new("enum");