newcover.go

Documentation: testing

     1  // Copyright 2022 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Support for test coverage with redesigned coverage implementation.
     6  
     7  package testing
     8  
     9  import (
    10  	"fmt"
    11  	"internal/goexperiment"
    12  	"os"
    13  )
    14  
    15  // cover2 variable stores the current coverage mode and a
    16  // tear-down function to be called at the end of the testing run.
    17  var cover2 struct {
    18  	mode        string
    19  	tearDown    func(coverprofile string, gocoverdir string) (string, error)
    20  	snapshotcov func() float64
    21  }
    22  
    23  // registerCover2 is invoked during "go test -cover" runs by the test harness
    24  // code in _testmain.go; it is used to record a 'tear down' function
    25  // (to be called when the test is complete) and the coverage mode.
    26  func registerCover2(mode string, tearDown func(coverprofile string, gocoverdir string) (string, error), snapcov func() float64) {
    27  	cover2.mode = mode
    28  	cover2.tearDown = tearDown
    29  	cover2.snapshotcov = snapcov
    30  }
    31  
    32  // coverReport2 invokes a callback in _testmain.go that will
    33  // emit coverage data at the point where test execution is complete,
    34  // for "go test -cover" runs.
    35  func coverReport2() {
    36  	if !goexperiment.CoverageRedesign {
    37  		panic("unexpected")
    38  	}
    39  	if errmsg, err := cover2.tearDown(*coverProfile, *gocoverdir); err != nil {
    40  		fmt.Fprintf(os.Stderr, "%s: %v\n", errmsg, err)
    41  		os.Exit(2)
    42  	}
    43  }
    44  
    45  // testGoCoverDir returns the value passed to the -test.gocoverdir
    46  // flag by the Go command, if goexperiment.CoverageRedesign is
    47  // in effect.
    48  func testGoCoverDir() string {
    49  	return *gocoverdir
    50  }
    51  
    52  // coverage2 returns a rough "coverage percentage so far"
    53  // number to support the testing.Coverage() function.
    54  func coverage2() float64 {
    55  	if cover2.mode == "" {
    56  		return 0.0
    57  	}
    58  	return cover2.snapshotcov()
    59  }
    60
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