snapshot_test.go

Documentation: internal/coverage/cfile

     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  //go:build SELECT_USING_THIS_TAG
     6  
     7  package cfile
     8  
     9  import "testing"
    10  
    11  var funcInvoked bool
    12  
    13  //go:noinline
    14  func thisFunctionOnlyCalledFromSnapshotTest(n int) int {
    15  	if funcInvoked {
    16  		panic("bad")
    17  	}
    18  	funcInvoked = true
    19  
    20  	// Contents here not especially important, just so long as we
    21  	// have some statements.
    22  	t := 0
    23  	for i := 0; i < n; i++ {
    24  		for j := 0; j < i; j++ {
    25  			t += i ^ j
    26  		}
    27  	}
    28  	return t
    29  }
    30  
    31  // Tests runtime/coverage.snapshot() directly. Note that if
    32  // coverage is not enabled, the hook is designed to just return
    33  // zero.
    34  func TestCoverageSnapshotImpl(t *testing.T) {
    35  	C1 := Snapshot()
    36  	thisFunctionOnlyCalledFromSnapshotTest(15)
    37  	C2 := Snapshot()
    38  	cond := "C1 > C2"
    39  	val := C1 > C2
    40  	if testing.CoverMode() != "" {
    41  		cond = "C1 >= C2"
    42  		val = C1 >= C2
    43  	}
    44  	t.Logf("%f %f\n", C1, C2)
    45  	if val {
    46  		t.Errorf("erroneous snapshots, %s = true C1=%f C2=%f",
    47  			cond, C1, C2)
    48  	}
    49  }
    50
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