Don't capitalize empty strings

Add tests for capitalize function

Author: thk123

src/util/string_utils.cpp

@@ -167,3 +167,11 @@ std::string escape_non_alnum(const std::string &to_escape)
   }
   return escaped.str();
 }
+std::string capitalize(const std::string &str)
+{
+  if(str.empty())
+    return str;
+  std::string capitalized = str;
+  capitalized[0] = toupper(capitalized[0]);
+  return capitalized;
+}

src/util/string_utils.h

@@ -18,6 +18,8 @@ Author: Daniel Poetzl
 
 std::string strip_string(const std::string &s);
 
+std::string capitalize(const std::string &str);
+
 /// Given a string s, split into a sequence of substrings when separated by
 /// specified delimiter.
 /// \param s: The string to split up

src/util/structured_data.cpp

@@ -5,13 +5,6 @@
 #include "string_utils.h"
 #include <algorithm>
 
-std::string capitalize(const std::string &str)
-{
-  std::string capitalized = str;
-  capitalized[0] = toupper(capitalized[0]);
-  return capitalized;
-}
-
 labelt::labelt(std::vector<std::string> components)
 {
   auto to_lower_string = [](const std::string &s) -> std::string {

unit/Makefile

@@ -98,6 +98,7 @@ SRC += analyses/ai/ai.cpp \
        util/std_expr.cpp \
        util/string2int.cpp \
        util/structured_data.cpp \
+       util/string_utils/capitalize.cpp \
        util/string_utils/join_string.cpp \
        util/string_utils/split_string.cpp \
        util/string_utils/strip_string.cpp \

unit/util/string_utils/capitalize.cpp

@@ -0,0 +1,14 @@
+// Copyright 2016-2020 Diffblue Limited. All Rights Reserved.
+
+#include <testing-utils/use_catch.h>
+#include <util/string_utils.h>
+
+TEST_CASE("capitalize", "[core][util][string_utils]")
+{
+  REQUIRE(capitalize("") == "");
+  REQUIRE(capitalize("abc") == "Abc");
+  REQUIRE(capitalize("aBc") == "ABc");
+  REQUIRE(capitalize("ABc") == "ABc");
+  REQUIRE(capitalize("abc def") == "Abc def");
+  REQUIRE(capitalize("1") == "1");
+}