Coverage Tutorial

The functions in the Instrumentation` context provide support for coverage reporting of WL code.

CoverageInstrument[inputDir,outputDir]	instrument WL code for coverage reporting
CoverageEvaluate[expr]	evaluate expr for coverage reporting
CoverageProcess[data,outputDir,lCovData]	process coverage data

Reporting coverage of WL code.

First we need to load the Instrumentation` package

Next we must instrument the code for coverage reporting.

Copy the original files to a temporary location.

Instrument the code and collect the baseline data.

Verify baselineData is present

Verify that instrumented code is found

Evaluate an expression for coverage reporting. We include the Needs because we want to include the code that runs at startup in the coverage report.

Verify runData

Process the coverage data

Now you must run the lcov and genhtml commands on the command-line.

lcov -a coverage-baseline.lcov -a coverage-run.lcov -o coverage-combined.lcov

genhtml --num-spaces 4 coverage-combined.lcov -o report

Below is a transcript of running the commands on a machine.

user@usermaclap Collatz % lcov -a coverage-baseline.lcov -a coverage-run.lcov -o coverage-combined.lcov
Combining tracefiles.
Reading tracefile coverage-baseline.lcov
Reading tracefile coverage-run.lcov
Writing data to coverage-combined.lcov
Summary coverage rate:
  lines......: 80.0% (4 of 5 lines)
  functions..: 80.0% (4 of 5 functions)
  branches...: no data found
  
user@usermaclap Collatz % genhtml --num-spaces 4 coverage-combined.lcov -o report
Reading data file coverage-combined.lcov
Found 1 entries.
Found common filename prefix "/private/var/folders/d_/tyn9s8p54fz2_zfvtx_frkb00000gn/T/Collatz-example/Collatz-orig"
Writing .css and .png files.
Generating output.
Processing file Collatz/Collatz.m
Writing directory view page.
Overall coverage rate:
  lines......: 80.0% (4 of 5 lines)
  functions..: 80.0% (4 of 5 functions)
user@usermaclap Collatz %

The report is generated in the report directory. The toplevel index page shows the line coverage and function coverage of each directory.

You can dig down to individual files and see line coverage and function coverage.

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