Check "Parsing JSON is a Minefield"

[nlohmann]

http://seriot.ch/parsing_json.html describes a lot of potential issues. We should have a look whether the library is affected.

[nlohmann]

Todo:

• Add the test files from https://github.com/nst/JSONTestSuite to the test suite
• Add test cases for the definite "yes" cases.
• Add test cases for the definite "no" cases.
• Investigate the "implementation-defined" cases.

[nlohmann]

Found 6 errors when parsing the "yes" cases:

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_array_empty.json
  parse error - unexpected end of input

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_object_empty.json
  parse error - unexpected end of input

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_string_space.json
  parse error - unexpected end of input

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_string_utf16.json
  parse error - unexpected '?'

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_structure_lonely_int.json
  parse error - unexpected end of input

src/unit-testsuites.cpp:551: FAILED:
  CHECK_NOTHROW( j << f )
due to unexpected exception with message:
  filename := test/data/nst_json_testsuite/test_parsing/y_structure_string_empty.json
  parse error - unexpected end of input

[nlohmann]

The UTF-16 test case (nst_json_testsuite/test_parsing/y_string_utf16.json) is the only missing failing test case. UTF-16 is not supported by this library. The README file should be adjusted accordingly.

[nlohmann]

From the "n" test cases, there are the following errors:

Unclear/to be checked:

• test/data/nst_json_testsuite/test_parsing/n_number_then_00.json

Overflow due to too deep nesting:

• test/data/nst_json_testsuite/test_parsing/n_structure_100000_opening_arrays.json
• test/data/nst_json_testsuite/test_parsing/n_structure_open_array_object.json

[nlohmann]

Merged fixes to develop branch. Scheduled for 2.0.7 release.

[t-b]

@nlohmann I've posted a PR on the nst test suite using a more-up-to-date version, see nst/JSONTestSuite#98.