Add tab as literal to cudf::test::to_string output (#13993)

Adds escaped `\\t` to the `cudf::test::to_string()` output.
Found this while working on #13891 where the output included tabs but was shown as a various number of spaces in the console when using `cudf::test::print()`.
Also added `\\b` for good measure as well as a gtest for all the supported escape sequences.

Authors:
  - David Wendt (https://github.com/davidwendt)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - Vukasin Milovanovic (https://github.com/vuule)

URL: #13993

cpp/tests/utilities/column_utilities.cu

@@ -1091,16 +1091,21 @@ struct column_view_printer {
     if (col.is_empty()) return;
     auto h_data = cudf::test::to_host<std::string>(col);
 
-    // explicitly replace '\r' and '\n' characters with "\r" and "\n" strings respectively.
+    // explicitly replace some special whitespace characters with their literal equivalents
     auto cleaned = [](std::string_view in) {
       std::string out(in);
       auto replace_char = [](std::string& out, char c, std::string_view repl) {
         for (std::string::size_type pos{}; out.npos != (pos = out.find(c, pos)); pos++) {
           out.replace(pos, 1, repl);
         }
       };
+      replace_char(out, '\a', "\\a");
+      replace_char(out, '\b', "\\b");
+      replace_char(out, '\f', "\\f");
       replace_char(out, '\r', "\\r");
+      replace_char(out, '\t', "\\t");
       replace_char(out, '\n', "\\n");
+      replace_char(out, '\v', "\\v");
       return out;
     };
 

cpp/tests/utilities_tests/column_utilities_tests.cpp

@@ -274,6 +274,14 @@ TEST_F(ColumnUtilitiesStringsTest, StringsToString)
   EXPECT_EQ(cudf::test::to_string(strings, delimiter), tmp.str());
 }
 
+TEST_F(ColumnUtilitiesStringsTest, PrintEscapeStrings)
+{
+  char const* delimiter = ",";
+  cudf::test::strings_column_wrapper input({"e\te\ne", "é\bé\ré", "e\vé\fé\abell"});
+  std::string expected{"e\\te\\ne,é\\bé\\ré,e\\vé\\fé\\abell"};
+  EXPECT_EQ(cudf::test::to_string(input, delimiter), expected);
+}
+
 TYPED_TEST(ColumnUtilitiesTestFixedPoint, NonNullableToHost)
 {
   using namespace numeric;