improved test coverage

README.md

@@ -449,7 +449,7 @@ $ make
 $ ./json_unit "*"
 
 ===============================================================================
-All tests passed (5568699 assertions in 31 test cases)
+All tests passed (5568703 assertions in 31 test cases)
 ```
 
 For more information, have a look at the file [.travis.yml](https://github.com/nlohmann/json/blob/master/.travis.yml).

src/json.hpp

@@ -9708,7 +9708,8 @@ basic_json_parser_63:
 
                     default:
                     {
-                        throw std::domain_error("unexpected parent type " + parent.type_name());
+                        // if there exists a parent it cannot be primitive
+                        assert(false);  // LCOV_EXCL_LINE
                     }
                 }
             }

src/json.hpp.re2c

@@ -9018,7 +9018,8 @@ class basic_json
 
                     default:
                     {
-                        throw std::domain_error("unexpected parent type " + parent.type_name());
+                        // if there exists a parent it cannot be primitive
+                        assert(false);  // LCOV_EXCL_LINE
                     }
                 }
             }

test/unit.cpp

@@ -12094,6 +12094,12 @@ TEST_CASE("JSON pointers")
 
         CHECK_THROWS_AS(json::json_pointer("/~"), std::domain_error);
         CHECK_THROWS_WITH(json::json_pointer("/~"), "escape error: '~' must be followed with '0' or '1'");
+
+        json::json_pointer p;
+        CHECK_THROWS_AS(p.top(), std::domain_error);
+        CHECK_THROWS_WITH(p.top(), "JSON pointer has no parent");
+        CHECK_THROWS_AS(p.pop_back(), std::domain_error);
+        CHECK_THROWS_WITH(p.pop_back(), "JSON pointer has no parent");
     }
 
     SECTION("examples from RFC 6901")