Cleanup some libcudf strings gtests (#9489)

Random gtests cleanup for some strings gtests:
- Reworked the class names to use the same base class in `substring_tests.cpp`, `pad_tests.cpp`, `char_types_tests.cpp`
- Renamed the regex-replace tests from `StringsReplaceTests` to `StringsReplaceRegexTest`
- Refactored code in `substring_tests.cpp` to simplify and organize the test clauses
- Renamed the utilities.cu to utilities.cpp (required no code change)

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

Approvers:
  - Karthikeyan (https://github.com/karthikeyann)
  - Bradley Dice (https://github.com/bdice)
  - Robert Maynard (https://github.com/robertmaynard)

URL: #9489

cpp/CMakeLists.txt

@@ -576,7 +576,7 @@ add_library(cudftestutil STATIC
             tests/utilities/column_utilities.cu
             tests/utilities/table_utilities.cu
             tests/io/metadata_utilities.cpp
-            tests/strings/utilities.cu)
+            tests/strings/utilities.cpp)
 
 set_target_properties(cudftestutil
     PROPERTIES BUILD_RPATH                         "\$ORIGIN"

cpp/src/hash/md5_hash.cu

@@ -238,6 +238,7 @@ struct HasherDispatcher {
                   std::is_same_v<Element, string_view>) {
       hasher->process(input_col.element<Element>(row_index));
     } else {
+      (void)row_index;
       cudf_assert(false && "Unsupported type for hash function.");
     }
   }
@@ -263,6 +264,8 @@ struct ListHasherDispatcher {
         if (input_col.is_valid(i)) { hasher->process(input_col.element<Element>(i)); }
       }
     } else {
+      (void)offset_begin;
+      (void)offset_end;
       cudf_assert(false && "Unsupported type for hash function.");
     }
   }

cpp/tests/strings/chars_types_tests.cpp

@@ -28,12 +28,11 @@
 struct StringsCharsTest : public cudf::test::BaseFixture {
 };
 
-class StringsCharsTestTypes
-  : public StringsCharsTest,
-    public testing::WithParamInterface<cudf::strings::string_character_types> {
+class CharsTypes : public StringsCharsTest,
+                   public testing::WithParamInterface<cudf::strings::string_character_types> {
 };
 
-TEST_P(StringsCharsTestTypes, AllTypes)
+TEST_P(CharsTypes, AllTypes)
 {
   std::vector<const char*> h_strings{"Héllo",
                                      "thesé",
@@ -84,8 +83,8 @@ TEST_P(StringsCharsTestTypes, AllTypes)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-INSTANTIATE_TEST_CASE_P(StringsCharsTestAllTypes,
-                        StringsCharsTestTypes,
+INSTANTIATE_TEST_CASE_P(StringsCharsTest,
+                        CharsTypes,
                         testing::ValuesIn(std::array<cudf::strings::string_character_types, 7>{
                           cudf::strings::string_character_types::DECIMAL,
                           cudf::strings::string_character_types::NUMERIC,

cpp/tests/strings/pad_tests.cpp

@@ -104,11 +104,10 @@ TEST_F(StringsPadTest, ZeroSizeStringsColumn)
   cudf::test::expect_strings_empty(results->view());
 }
 
-class StringsPadParmsTest : public StringsPadTest,
-                            public testing::WithParamInterface<cudf::size_type> {
+class PadParameters : public StringsPadTest, public testing::WithParamInterface<cudf::size_type> {
 };
 
-TEST_P(StringsPadParmsTest, Padding)
+TEST_P(PadParameters, Padding)
 {
   std::vector<std::string> h_strings{"eee ddd", "bb cc", "aa", "bbb", "fff", "", "o"};
   cudf::test::strings_column_wrapper strings(h_strings.begin(), h_strings.end());
@@ -128,8 +127,8 @@ TEST_P(StringsPadParmsTest, Padding)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-INSTANTIATE_TEST_CASE_P(StringsPadParmWidthTest,
-                        StringsPadParmsTest,
+INSTANTIATE_TEST_CASE_P(StringsPadTest,
+                        PadParameters,
                         testing::ValuesIn(std::array<cudf::size_type, 3>{5, 6, 7}));
 
 TEST_F(StringsPadTest, ZFill)

cpp/tests/strings/replace_regex_tests.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2020, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2021, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,10 +23,10 @@
 
 #include <vector>
 
-struct StringsReplaceTests : public cudf::test::BaseFixture {
+struct StringsReplaceRegexTest : public cudf::test::BaseFixture {
 };
 
-TEST_F(StringsReplaceTests, ReplaceRegexTest)
+TEST_F(StringsReplaceRegexTest, ReplaceRegexTest)
 {
   std::vector<const char*> h_strings{"the quick brown fox jumps over the lazy dog",
                                      "the fat cat lays next to the other accénted cat",
@@ -59,7 +59,7 @@ TEST_F(StringsReplaceTests, ReplaceRegexTest)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, ReplaceMultiRegexTest)
+TEST_F(StringsReplaceRegexTest, ReplaceMultiRegexTest)
 {
   std::vector<const char*> h_strings{"the quick brown fox jumps over the lazy dog",
                                      "the fat cat lays next to the other accénted cat",
@@ -95,7 +95,7 @@ TEST_F(StringsReplaceTests, ReplaceMultiRegexTest)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, InvalidRegex)
+TEST_F(StringsReplaceRegexTest, InvalidRegex)
 {
   cudf::test::strings_column_wrapper strings(
     {"abc*def|ghi+jkl", ""});  // these do not really matter
@@ -116,7 +116,7 @@ TEST_F(StringsReplaceTests, InvalidRegex)
                cudf::logic_error);
 }
 
-TEST_F(StringsReplaceTests, WithEmptyPattern)
+TEST_F(StringsReplaceRegexTest, WithEmptyPattern)
 {
   std::vector<const char*> h_strings{"asd", "xcv"};
   cudf::test::strings_column_wrapper strings(
@@ -133,7 +133,7 @@ TEST_F(StringsReplaceTests, WithEmptyPattern)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, strings);
 }
 
-TEST_F(StringsReplaceTests, ReplaceBackrefsRegexTest)
+TEST_F(StringsReplaceRegexTest, ReplaceBackrefsRegexTest)
 {
   std::vector<const char*> h_strings{"the quick brown fox jumps over the lazy dog",
                                      "the fat cat lays next to the other accénted cat",
@@ -167,7 +167,7 @@ TEST_F(StringsReplaceTests, ReplaceBackrefsRegexTest)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, ReplaceBackrefsRegexAltIndexPatternTest)
+TEST_F(StringsReplaceRegexTest, ReplaceBackrefsRegexAltIndexPatternTest)
 {
   cudf::test::strings_column_wrapper strings({"12-3 34-5 67-89", "0-99: 777-888:: 5673-0"});
   auto strings_view = cudf::strings_column_view(strings);
@@ -181,7 +181,7 @@ TEST_F(StringsReplaceTests, ReplaceBackrefsRegexAltIndexPatternTest)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, ReplaceBackrefsRegexReversedTest)
+TEST_F(StringsReplaceRegexTest, ReplaceBackrefsRegexReversedTest)
 {
   cudf::test::strings_column_wrapper strings(
     {"A543", "Z756", "", "tést-string", "two-thréé four-fivé", "abcd-éfgh", "tést-string-again"});
@@ -200,7 +200,7 @@ TEST_F(StringsReplaceTests, ReplaceBackrefsRegexReversedTest)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, BackrefWithGreedyQuantifier)
+TEST_F(StringsReplaceRegexTest, BackrefWithGreedyQuantifier)
 {
   cudf::test::strings_column_wrapper input(
     {"<h1>title</h1><h2>ABC</h2>", "<h1>1234567</h1><h2>XYZ</h2>"});
@@ -217,7 +217,7 @@ TEST_F(StringsReplaceTests, BackrefWithGreedyQuantifier)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, ReplaceBackrefsRegexErrorTest)
+TEST_F(StringsReplaceRegexTest, ReplaceBackrefsRegexErrorTest)
 {
   cudf::test::strings_column_wrapper strings({"this string left intentionally blank"});
   auto view = cudf::strings_column_view(strings);
@@ -228,7 +228,7 @@ TEST_F(StringsReplaceTests, ReplaceBackrefsRegexErrorTest)
   EXPECT_THROW(cudf::strings::replace_with_backrefs(view, "(\\w)", ""), cudf::logic_error);
 }
 
-TEST_F(StringsReplaceTests, MediumReplaceRegex)
+TEST_F(StringsReplaceRegexTest, MediumReplaceRegex)
 {
   // This results in 95 regex instructions and falls in the 'medium' range.
   std::string medium_regex =
@@ -256,7 +256,7 @@ TEST_F(StringsReplaceTests, MediumReplaceRegex)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected);
 }
 
-TEST_F(StringsReplaceTests, LargeReplaceRegex)
+TEST_F(StringsReplaceRegexTest, LargeReplaceRegex)
 {
   // This results in 117 regex instructions and falls in the 'large' range.
   std::string large_regex =