Language field contains the following invalid language tags:
  en_GB
Language field contains the following invalid language tags:
  en_GB
Language field contains the following invalid language tags:
  en_GB
Language field contains the following invalid language tags:
  en_GB
Language field contains the following invalid language tags:
  en_GB

installed size is 11.0Mb
  sub-directories of 1Mb or more:
    include   6.3Mb
    libs      4.6Mb
installed size is 11.2Mb
  sub-directories of 1Mb or more:
    include   6.3Mb
    libs      4.8Mb
installed size is  7.8Mb
  sub-directories of 1Mb or more:
    include   6.5Mb
    libs      1.2Mb
installed size is 11.0Mb
  sub-directories of 1Mb or more:
    include   6.3Mb
    libs      4.6Mb
installed size is 11.2Mb
  sub-directories of 1Mb or more:
    include   6.3Mb
    libs      4.8Mb
installed size is  7.9Mb
  sub-directories of 1Mb or more:
    include   6.5Mb
    libs      1.3Mb

File ‘RFpredInterval/libs/RFpredInterval.so’:
  Found non-API call to R: ‘STRING_PTR’

Compiled code should not call non-API entry points in R.

See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
and section ‘Moving into C API compliance’ for issues with the use of
non-API entry points.
File ‘RFpredInterval/libs/RFpredInterval.so’:
  Found non-API call to R: ‘STRING_PTR’

Compiled code should not call non-API entry points in R.

See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
and section ‘Moving into C API compliance’ for issues with the use of
non-API entry points.
File ‘RFpredInterval/libs/RFpredInterval.so’:
  Found non-API call to R: ‘STRING_PTR’

Compiled code should not call non-API entry points in R.

See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
and section ‘Moving into C API compliance’ for issues with the use of
non-API entry points.
File ‘RFpredInterval/libs/RFpredInterval.so’:
  Found non-API call to R: ‘STRING_PTR’

Compiled code should not call non-API entry points in R.

See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
and section ‘Moving into C API compliance’ for issues with the use of
non-API entry points.
File 'RFpredInterval/libs/x64/RFpredInterval.dll':
  Found non-API call to R: 'STRING_PTR'

Compiled code should not call non-API entry points in R.

See 'Writing portable packages' in the 'Writing R Extensions' manual,
and section 'Moving into C API compliance' for issues with the use of
non-API entry points.
Running 'testthat.R' [11s]
Running the tests in 'tests/testthat.R' failed.
Complete output:
  > library(testthat)
  > library(RFpredInterval)
  RFpredInterval 1.0.8 
  
  > 
  > test_check("RFpredInterval")