pseudo: improve overflow message; add overflow test

src/cmd/pseudo.rs

@@ -135,9 +135,9 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
             });
             if overflowed {
                 return fail_incorrectusage_clierror!(
-                    "Overflowed. The increment value is too large. The maximum value for \
-                     --increment is {}.",
-                    u64::MAX - curr_counter
+                    "Overflowed. The counter is larger than u64::MAX {}. The last valid counter \
+                     is {curr_counter}.",
+                    u64::MAX
                 );
             }
             record = replace_column_value(&record, column_index, &new_value.to_string());
@@ -175,9 +175,9 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
             });
             if overflowed {
                 return fail_incorrectusage_clierror!(
-                    "Overflowed. The increment value is too large. The maximum value for \
-                     --increment is {}.",
-                    u64::MAX - curr_counter
+                    "Overflowed. The counter is larger than u64::MAX({}). The last valid counter \
+                     is {curr_counter}.",
+                    u64::MAX
                 );
             }
 

tests/test_pseudo.rs

@@ -161,3 +161,44 @@ fn pseudo_formatstr_start_increment() {
     ];
     assert_eq!(got, expected);
 }
+
+#[test]
+fn pseudo_overflow() {
+    let wrk = Workdir::new("pseudo_overflow");
+    wrk.create(
+        "data.csv",
+        vec![
+            svec!["name", "colors"],
+            svec!["Mary", "yellow"],
+            svec!["John", "blue"],
+            svec!["Mary", "purple"],
+            svec!["Sue", "orange"],
+            svec!["John", "magenta"],
+            svec!["Mary", "cyan"],
+        ],
+    );
+    let close_to_max = std::u64::MAX - 10;
+    let mut cmd = wrk.command("pseudo");
+    cmd.arg("name")
+        .args(["--formatstr", "ID-{}"])
+        .args(["--start", close_to_max.to_string().as_str()])
+        .args(["--increment", "5"])
+        .arg("data.csv");
+
+    wrk.assert_err(&mut cmd);
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = vec![
+        svec!["name", "colors"],
+        svec!["ID-18446744073709551605", "yellow"],
+        svec!["ID-18446744073709551610", "blue"],
+        svec!["ID-18446744073709551605", "purple"],
+    ];
+    assert_eq!(got, expected);
+
+    let got_err = wrk.output_stderr(&mut cmd);
+    assert_eq!(
+        got_err,
+        "usage error: Overflowed. The counter is larger than u64::MAX(18446744073709551615). The \
+         last valid counter is 18446744073709551615.\n"
+    );
+}