distribution/context/trace_test.go

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package context
import (
"context"
"runtime"
"testing"
"time"
)
// TestWithTrace ensures that tracing has the expected values in the context.
func TestWithTrace(t *testing.T) {
pc, file, _, _ := runtime.Caller(0) // get current caller.
f := runtime.FuncForPC(pc)
base := []valueTestCase{
{
key: "trace.id",
notnilorempty: true,
},
{
key: "trace.file",
expected: file,
notnilorempty: true,
},
{
key: "trace.line",
notnilorempty: true,
},
{
key: "trace.start",
notnilorempty: true,
},
}
ctx, done := WithTrace(Background())
defer done("this will be emitted at end of test")
checkContextForValues(ctx, t, append(base, valueTestCase{
key: "trace.func",
expected: f.Name(),
}))
traced := func() {
parentID := ctx.Value("trace.id") // ensure the parent trace id is correct.
pc, _, _, _ := runtime.Caller(0) // get current caller.
f := runtime.FuncForPC(pc)
ctx, done := WithTrace(ctx)
defer done("this should be subordinate to the other trace")
time.Sleep(time.Second)
checkContextForValues(ctx, t, append(base, valueTestCase{
key: "trace.func",
expected: f.Name(),
}, valueTestCase{
key: "trace.parent.id",
expected: parentID,
}))
}
traced()
time.Sleep(time.Second)
}
type valueTestCase struct {
key string
expected interface{}
notnilorempty bool // just check not empty/not nil
}
func checkContextForValues(ctx context.Context, t *testing.T, values []valueTestCase) {
for _, testcase := range values {
v := ctx.Value(testcase.key)
if testcase.notnilorempty {
if v == nil || v == "" {
t.Fatalf("value was nil or empty for %q: %#v", testcase.key, v)
}
continue
}
if v != testcase.expected {
t.Fatalf("unexpected value for key %q: %v != %v", testcase.key, v, testcase.expected)
}
}
}