testing, internal/fuzz: Support -c flag

[AdamKorcz]

When building a native fuzzer with the -c flag, a unit test is built.

For example, I have a simple fuzzer:

package fuzz

import (
        "fmt"
        "testing"
)

func Fuzz(f *testing.F) {
        f.Fuzz(func(t *testing.T, data string) {
                fmt.Println(data)
        })
}

I build it with go test -fuzz=Fuzz -c
...which gives me the fuzz.test executable.
Running that executable with ./fuzz.test prints out: PASS

This may be intended, but it would be highly desirable to offer support for building an executable that can be run with the same flags as go test -fuzz=Fuzz.

[seankhliao]

You need to pass the fuzz flags (like any other test flags) to the built binary, not to the build command.

For questions please refer to https://github.com/golang/go/wiki/Questions

[AdamKorcz]

./fuzz.test -test.fuzztime 20s also prints out PASS

[seankhliao]

./fuzz.test -test.fuzz=Fuzz

[AdamKorcz]

./fuzz.test -test.fuzz=Fuzz

Thank you. That is partially correct. The result of that command alone is:

testing: -test.fuzzcachedir must be set if -test.fuzz is set
Usage of ./fuzz.test:                                                                     
  -test.bench regexp                                                                      
        run only benchmarks matching regexp
  -test.benchmem                                                                          
        print memory allocations for benchmarks  
  -test.benchtime d                                                                                                                                                                  
        run each benchmark for duration d (default 1s)
  -test.blockprofile file                                                                 
        write a goroutine blocking profile to file                           
  -test.blockprofilerate rate
        set blocking profile rate (see runtime.SetBlockProfileRate) (default 1)
  -test.count n                                                                           
        run tests and benchmarks n times (default 1)                                                                                                                                 
  -test.coverprofile file
        write a coverage profile to file
  -test.cpu list
        comma-separated list of cpu counts to run each test with
  -test.cpuprofile file
        write a cpu profile to file
  -test.failfast
        do not start new tests after the first test failure
  -test.fuzz regexp
        run the fuzz test matching regexp
  -test.fuzzcachedir string
        directory where interesting fuzzing inputs are stored (for use only by cmd/go)
  -test.fuzzminimizetime value
        time to spend minimizing a value after finding a failing input (default 1m0s)
  -test.fuzztime value
        time to spend fuzzing; default is to run indefinitely
  -test.fuzzworker
        coordinate with the parent process to fuzz random values (for use only by cmd/go)
  -test.list regexp
        list tests, examples, and benchmarks matching regexp then exit
  -test.memprofile file
        write an allocation profile to file
  -test.memprofilerate rate
        set memory allocation profiling rate (see runtime.MemProfileRate)
  -test.mutexprofile string
        write a mutex contention profile to the named file after execution
  -test.mutexprofilefraction int
        if >= 0, calls runtime.SetMutexProfileFraction() (default 1)
  -test.outputdir dir
        write profiles to dir
  -test.paniconexit0
        panic on call to os.Exit(0)
  -test.parallel n
        run at most n tests in parallel (default 5)
  -test.run regexp
        run only tests and examples matching regexp
  -test.short
        run smaller test suite to save time
  -test.shuffle string
        randomize the execution order of tests and benchmarks (default "off")
  -test.testlogfile file
        write test action log to file (for use only by cmd/go)
  -test.timeout d
        panic test binary after duration d (default 0, timeout disabled)
  -test.trace file
        write an execution trace to file
  -test.v
        verbose: print additional output

And as is mentioned on the first line, if we create an empty directory and run ./fuzz.test -test.fuzz=Fuzz -test.fuzzcachedir $PWD/cachedir/, then it works.

Thank you very much for the quick reply, @seankhliao