trace_test.go

Documentation: github.com/docker/distribution/context

     1  package context
     2  
     3  import (
     4  	"context"
     5  	"runtime"
     6  	"testing"
     7  	"time"
     8  )
     9  
    10  // TestWithTrace ensures that tracing has the expected values in the context.
    11  func TestWithTrace(t *testing.T) {
    12  	pc, file, _, _ := runtime.Caller(0) // get current caller.
    13  	f := runtime.FuncForPC(pc)
    14  
    15  	base := []valueTestCase{
    16  		{
    17  			key:           "trace.id",
    18  			notnilorempty: true,
    19  		},
    20  
    21  		{
    22  			key:           "trace.file",
    23  			expected:      file,
    24  			notnilorempty: true,
    25  		},
    26  		{
    27  			key:           "trace.line",
    28  			notnilorempty: true,
    29  		},
    30  		{
    31  			key:           "trace.start",
    32  			notnilorempty: true,
    33  		},
    34  	}
    35  
    36  	ctx, done := WithTrace(Background())
    37  	defer done("this will be emitted at end of test")
    38  
    39  	checkContextForValues(ctx, t, append(base, valueTestCase{
    40  		key:      "trace.func",
    41  		expected: f.Name(),
    42  	}))
    43  
    44  	traced := func() {
    45  		parentID := ctx.Value("trace.id") // ensure the parent trace id is correct.
    46  
    47  		pc, _, _, _ := runtime.Caller(0) // get current caller.
    48  		f := runtime.FuncForPC(pc)
    49  		ctx, done := WithTrace(ctx)
    50  		defer done("this should be subordinate to the other trace")
    51  		time.Sleep(time.Second)
    52  		checkContextForValues(ctx, t, append(base, valueTestCase{
    53  			key:      "trace.func",
    54  			expected: f.Name(),
    55  		}, valueTestCase{
    56  			key:      "trace.parent.id",
    57  			expected: parentID,
    58  		}))
    59  	}
    60  	traced()
    61  
    62  	time.Sleep(time.Second)
    63  }
    64  
    65  type valueTestCase struct {
    66  	key           string
    67  	expected      interface{}
    68  	notnilorempty bool // just check not empty/not nil
    69  }
    70  
    71  func checkContextForValues(ctx context.Context, t *testing.T, values []valueTestCase) {
    72  	for _, testcase := range values {
    73  		v := ctx.Value(testcase.key)
    74  		if testcase.notnilorempty {
    75  			if v == nil || v == "" {
    76  				t.Fatalf("value was nil or empty for %q: %#v", testcase.key, v)
    77  			}
    78  			continue
    79  		}
    80  
    81  		if v != testcase.expected {
    82  			t.Fatalf("unexpected value for key %q: %v != %v", testcase.key, v, testcase.expected)
    83  		}
    84  	}
    85  }
    86
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