Add AddCallers() and additional test cases around callers functionality

field_test.go

@@ -228,10 +228,22 @@ func TestStackField(t *testing.T) {
 func TestCaller(t *testing.T) {
 	// Caller() makes an assupmtion that it is called within zap's hook mechanism.
 	// This is not true for this test, so pass -1 to log this function as the caller.
-	c, _ := Caller(-1)
+	c, ok := Caller(-1)
+	assert.NoError(t, ok, "Caller should not return an error ")
 	assertFieldJSONRegEx(t, "\"caller\":{\"pc\":[0-9]+,\"file\":\".+field_test.go\",\"line\":[0-9]+}", c)
 
-	c2, _ := Caller(-1)
+	c2, ok := Caller(-1)
+	assert.NoError(t, ok, "Caller should not return an error ")
+	assertCanBeReused(t, c2)
+}
+
+func TestCallers(t *testing.T) {
+	// Caller() makes an assupmtion that it is called within zap's hook mechanism.
+	// This is not true for this test, so pass 0 to log this function as the caller.
+	c := Callers(0)
+	assertFieldJSONRegEx(t, "\"callers\":{\"0\":{\"pc\":[0-9]+,\"file\":\".+field_test.go\",\"line\":[0-9]+},", c)
+
+	c2 := Callers(0)
 	assertCanBeReused(t, c2)
 }
 

hook.go

@@ -71,9 +71,15 @@ func AddCallerWithSkip(callerSkip int) Option {
 	})
 }
 
-// AddCallersWithSkip records the caller's call stack for all messages at or above a given level.
-// The callerskip option helps select the target caller.  Using a value of _callerSkip will select
+// AddCallers records the caller's call stack for all messages at or above a given level.
+// This uses _callerSkip for the caller skip, which will select
 // the target caller as the caller of the leveled logger method.
+func AddCallers(lvl Level) Option {
+	return AddCallersWithSkip(_callersSkip, lvl)
+}
+
+// AddCallersWithSkip records the caller's call stack for all messages at or above a given level.
+// The callerskip option helps select the target caller.
 func AddCallersWithSkip(callerSkip int, lvl Level) Option {
 	return Hook(func(e *Entry) error {
 		if e == nil {

hook_test.go

@@ -56,6 +56,24 @@ func TestHookAddCallerFail(t *testing.T) {
 	assert.Contains(t, buf.String(), `"msg":"Failure."`, "Expected original message to survive failures in runtime.Caller.")
 }
 
+func TestHookAddCallers(t *testing.T) {
+	buf := &testBuffer{}
+	logger := New(NewJSONEncoder(), DebugLevel, Output(buf), AddCallers(InfoLevel))
+
+	logger.Info("Callers.")
+	output := buf.String()
+	require.Contains(t, output, "zap/hook_test.go", "Expected to find test file in callers.")
+	assert.Contains(t, output, `"callers":`, "Callers added under an unexpected key.")
+
+	buf.Reset()
+	logger.Warn("Callers.")
+	assert.Contains(t, buf.String(), `"callers":`, "Expected to include callers at Warn level.")
+
+	buf.Reset()
+	logger.Debug("No callers.")
+	assert.NotContains(t, buf.String(), "Unexpected stacktrace at Debug level.")
+}
+
 func TestHookAddCallersWithSkip(t *testing.T) {
 	buf := &testBuffer{}
 	logger := New(NewJSONEncoder(), DebugLevel, Output(buf), AddCallersWithSkip(_callersSkip, InfoLevel))