Add required tests for go/tb (#15063)

Signed-off-by: Noble Mittal <[email protected]>

go/tb/error_test.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tb
+
+import (
+	"bytes"
+	"fmt"
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStackTrace(t *testing.T) {
+	testErr := "test err"
+	testStackTrace := "test stack trace"
+	testStackError := stackError{
+		err:        fmt.Errorf("%s", testErr),
+		stackTrace: testStackTrace,
+	}
+
+	expectedErr := fmt.Sprintf("%s\n%s", testErr, testStackTrace)
+	assert.Equal(t, expectedErr, testStackError.Error())
+	assert.Equal(t, testStackTrace, testStackError.StackTrace())
+}
+
+func TestStack(t *testing.T) {
+	// skip is set to 2 to check if the 3rd function in
+	// the go routine stack is called from this file
+	// 1st func is expected to be stack and 2nd to be Stack
+	b := Stack(2)
+	l := bytes.Split(b, []byte(":"))
+
+	_, file, _, _ := runtime.Caller(0)
+	assert.Equal(t, string(l[0]), file)
+}
+
+func TestFunction(t *testing.T) {
+	pc, _, _, _ := runtime.Caller(0)
+	name := function(pc)
+
+	assert.Equal(t, "io/vitess/go/tb.TestFunction", string(name))
+
+	// invalid program counter
+	name = function(0)
+	assert.Equal(t, name, dunno)
+}
+
+func TestErrorf(t *testing.T) {
+	s1 := stackError{
+		err:        fmt.Errorf("err1"),
+		stackTrace: "stackTrace1",
+	}
+	s2 := stackError{
+		err:        fmt.Errorf("err2"),
+		stackTrace: "stackTrace2",
+	}
+	err := Errorf("test msg %v %v", s1, s2)
+
+	expectedMsg := fmt.Sprintf("test msg %v %v", s1, s2)
+	expectedErr := fmt.Sprintf("%v\n%v", expectedMsg, "stackTrace1")
+	assert.Equal(t, err.Error(), expectedErr)
+
+	err = Errorf("test msg")
+	s := string(Stack(4))
+	expectedErr = fmt.Sprintf("%v\n%v", "test msg", s)
+	assert.Equal(t, err.Error(), expectedErr)
+}
+
+func TestSource(t *testing.T) {
+	lines := [][]byte{
+		[]byte("\ttest line 1\t"),
+		[]byte("\ttest line 2\t"),
+		[]byte("\ttest line 3\t"),
+	}
+
+	assert.Equal(t, []byte("test line 1"), source(lines, 0))
+	assert.Equal(t, []byte("test line 2"), source(lines, 1))
+	assert.Equal(t, dunno, source(lines, -1))
+	assert.Equal(t, dunno, source(lines, 3))
+}