Merge pull request #132 from skrobinson/feat-improve-errors

Improve error messages

include/argparse/argparse.hpp

@@ -472,7 +472,8 @@ public:
     } else if (mDefaultValue.has_value()) {
       return start;
     } else {
-      throw std::runtime_error("Too few arguments");
+      throw std::runtime_error("Too few arguments for '" +
+                               std::string(mUsedName) + "'.");
     }
   }
 
@@ -759,7 +760,7 @@ private:
     if (mDefaultValue.has_value()) {
       return std::any_cast<T>(mDefaultValue);
     }
-    throw std::logic_error("No value provided");
+    throw std::logic_error("No value provided for '" + mNames.back() + "'.");
   }
 
   /*
@@ -910,12 +911,16 @@ public:
   }
 
   /* Getter for options with default values.
+   * @throws std::logic_error if parse_args() has not been previously called
    * @throws std::logic_error if there is no such option
    * @throws std::logic_error if the option has no value
    * @throws std::bad_any_cast if the option is not of type T
    */
   template <typename T = std::string>
   T get(std::string_view aArgumentName) const {
+    if (!mIsParsed) {
+      throw std::logic_error("Nothing parsed, no arguments are available.");
+    }
     return (*this)[aArgumentName].get<T>();
   }
 
@@ -1075,6 +1080,7 @@ private:
         throw std::runtime_error("Unknown argument");
       }
     }
+    mIsParsed = true;
   }
 
   /*
@@ -1114,6 +1120,7 @@ private:
   std::string mVersion;
   std::string mDescription;
   std::string mEpilog;
+  bool mIsParsed = false;
   std::list<Argument> mPositionalArguments;
   std::list<Argument> mOptionalArguments;
   std::map<std::string_view, list_iterator, std::less<>> mArgumentMap;

test/CMakeLists.txt

@@ -30,6 +30,7 @@ file(GLOB ARGPARSE_TEST_SOURCES
     test_compound_arguments.cpp
     test_container_arguments.cpp
     test_const_correct.cpp
+    test_get.cpp
     test_help.cpp
     test_invalid_arguments.cpp
     test_is_used.cpp

test/test_get.cpp

@@ -0,0 +1,37 @@
+#include <doctest.hpp>
+#include <argparse/argparse.hpp>
+
+using doctest::test_suite;
+
+TEST_CASE("Getting a simple argument" * test_suite("ArgumentParser::get")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("-s", "--stuff");
+  REQUIRE_NOTHROW(program.parse_args({ "test", "-s", "./src" }));
+  REQUIRE(program.get("--stuff") == "./src");
+}
+
+TEST_CASE("Skipped call to parse_args" * test_suite("ArgumentParser::get")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("stuff");
+  REQUIRE_THROWS_WITH_AS(program.get("stuff"),
+                         "Nothing parsed, no arguments are available.",
+                         std::logic_error);
+}
+
+TEST_CASE("Missing argument" * test_suite("ArgumentParser::get")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("-s", "--stuff");
+  REQUIRE_NOTHROW(program.parse_args({ "test" }));
+  REQUIRE_THROWS_WITH_AS(program.get("--stuff"),
+                         "No value provided for '--stuff'.",
+                         std::logic_error);
+}
+
+TEST_CASE("Implicit argument" * test_suite("ArgumentParser::get")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("-s", "--stuff").nargs(1);
+  REQUIRE_NOTHROW(program.parse_args({ "test" }));
+  REQUIRE_THROWS_WITH_AS(program.get("--stuff"),
+                         "No value provided for '--stuff'.",
+                         std::logic_error);
+}

test/test_parse_args.cpp

@@ -3,6 +3,14 @@
 
 using doctest::test_suite;
 
+TEST_CASE("Missing argument" * test_suite("parse_args")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("--config").nargs(1);
+  REQUIRE_THROWS_WITH_AS(program.parse_args({ "test", "--config" }),
+                         "Too few arguments for '--config'.",
+                         std::runtime_error);
+}
+
 TEST_CASE("Parse a string argument with value" * test_suite("parse_args")) {
   argparse::ArgumentParser program("test");
   program.add_argument("--config");

test/test_positional_arguments.cpp

@@ -13,6 +13,15 @@ TEST_CASE("Parse positional arguments" * test_suite("positional_arguments")) {
   REQUIRE(program.get("output") == "thrust_profile.csv");
 }
 
+TEST_CASE("Missing expected positional argument" *
+          test_suite("positional_arguments")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("input");
+  REQUIRE_THROWS_WITH_AS(program.parse_args({ "test" }),
+                         "1 argument(s) expected. 0 provided.",
+                         std::runtime_error);
+}
+
 TEST_CASE("Parse positional arguments with fixed nargs" *
           test_suite("positional_arguments")) {
   argparse::ArgumentParser program("test");