add stacktrace to chain and formatted data

assertion.go

@@ -192,6 +192,9 @@ type AssertionFailure struct {
 
 	// Allowed delta between actual and expected
 	Delta *AssertionValue
+
+	// Stacktrace of a fail
+	Stacktrace []CallerInfo
 }
 
 // AssertionValue holds expected or actual value

chain.go

@@ -2,6 +2,7 @@ package httpexpect
 
 import (
 	"fmt"
+	"runtime"
 	"sync"
 	"testing"
 
@@ -435,6 +436,9 @@ func (c *chain) fail(failure AssertionFailure) {
 	if c.severity == SeverityError {
 		failure.IsFatal = true
 	}
+
+	failure.Stacktrace = GetCallerInfo()
+
 	c.failure = &failure
 }
 
@@ -502,3 +506,41 @@ func isTestingTB(in AssertionHandler) bool {
 	}
 	return false
 }
+
+type CallerInfo struct {
+	FuncName string
+	File     string
+	Line     int
+}
+
+func GetCallerInfo() []CallerInfo {
+	callers := []CallerInfo{}
+	for i := 0; ; i++ {
+		pc, file, line, ok := runtime.Caller(i)
+		if !ok {
+			break
+		}
+
+		if file == "<autogenerated>" {
+			break
+		}
+
+		f := runtime.FuncForPC(pc)
+		if f == nil {
+			break
+		}
+		funcName := f.Name()
+
+		if funcName == "testing.tRunner" {
+			break
+		}
+
+		callers = append(callers, CallerInfo{
+			FuncName: funcName,
+			File:     file,
+			Line:     line,
+		})
+	}
+
+	return callers
+}

chain_test.go

@@ -674,6 +674,22 @@ func TestChain_Severity(t *testing.T) {
 	})
 }
 
+func TestChain_Stacktrace(t *testing.T) {
+	handler := &mockAssertionHandler{}
+
+	chain := newChainWithConfig("test", Config{
+		AssertionHandler: handler,
+	}.withDefaults())
+
+	opChain := chain.enter("test")
+	opChain.fail(testFailure())
+	opChain.leave()
+
+	assert.True(t, opChain.failed())
+	assert.NotNil(t, handler.failure)
+	assert.NotEmpty(t, handler.failure.Stacktrace)
+}
+
 func TestChain_Reporting(t *testing.T) {
 	handler := &mockAssertionHandler{}
 
@@ -708,6 +724,8 @@ func TestChain_Reporting(t *testing.T) {
 	assert.True(t, chain.failed())   // reported to parent
 	assert.NotNil(t, handler.ctx)    // reported to handler
 	assert.NotNil(t, handler.failure)
+
+	failure.Stacktrace = handler.failure.Stacktrace
 	assert.Equal(t, failure, *handler.failure)
 }
 

formatter.go

@@ -58,6 +58,9 @@ type DefaultFormatter struct {
 	// Exclude HTTP response from failure report.
 	DisableResponses bool
 
+	// Enables printing of stacktrace on failure
+	StacktraceMode StacktraceMode
+
 	// Thousand separator.
 	// Default is DigitSeparatorUnderscore.
 	DigitSeparator DigitSeparator
@@ -112,6 +115,16 @@ func (f *DefaultFormatter) FormatFailure(
 	}
 }
 
+type StacktraceMode int
+
+const (
+	// Unconditionally disable stacktrace.
+	StacktraceModeDisabled StacktraceMode = iota
+
+	// Format caller info as `at [function name]([file]:[line])`
+	StacktraceModeDefault
+)
+
 // DigitSeparator defines the separator used to format integers and floats.
 type DigitSeparator int
 
@@ -209,6 +222,9 @@ type FormatData struct {
 	HaveResponse bool
 	Response     string
 
+	HaveStacktrace bool
+	Stacktrace     []string
+
 	EnableColors bool
 	LineWidth    int
 }
@@ -284,6 +300,7 @@ func (f *DefaultFormatter) buildFormatData(
 
 		f.fillRequest(&data, ctx, failure)
 		f.fillResponse(&data, ctx, failure)
+		f.fillStacktrace(&data, ctx, failure)
 	}
 
 	return &data
@@ -546,6 +563,23 @@ func (f *DefaultFormatter) fillResponse(
 	}
 }
 
+func (f *DefaultFormatter) fillStacktrace(
+	data *FormatData, ctx *AssertionContext, failure *AssertionFailure,
+) {
+	data.Stacktrace = []string{}
+
+	if f.StacktraceMode == StacktraceModeDisabled {
+		return
+	}
+	if f.StacktraceMode == StacktraceModeDefault {
+		for _, call := range failure.Stacktrace {
+			formatted := fmt.Sprintf("at %s(%s:%d)", call.FuncName, call.File, call.Line)
+			data.Stacktrace = append(data.Stacktrace, formatted)
+		}
+		data.HaveStacktrace = len(failure.Stacktrace) != 0
+	}
+}
+
 func (f *DefaultFormatter) formatValue(value interface{}) string {
 	if flt := extractFloat32(value); flt != nil {
 		return f.reformatNumber(f.formatFloatValue(*flt, 32))
@@ -1016,6 +1050,13 @@ request: {{ .Request | indent | trim | color $.EnableColors "HiMagenta" }}
 
 response: {{ .Response | indent | trim | color $.EnableColors "HiMagenta" }}
 {{- end -}}
+{{- if .HaveStacktrace }}
+
+trace:
+{{- range $n, $call := .Stacktrace }}
+{{ $call | indent }}
+{{- end -}}
+{{- end -}}
 {{- if .AssertPath }}
 
 assertion:

formatter_test.go

@@ -1056,3 +1056,48 @@ func TestFormatter_ColorMode(t *testing.T) {
 		})
 	}
 }
+
+func TestFormatter_Stacktrace(t *testing.T) {
+	df := &DefaultFormatter{
+		StacktraceMode: StacktraceModeDefault,
+	}
+	ctx := &AssertionContext{}
+
+	cases := []struct {
+		callerInfo CallerInfo
+		want       string
+	}{
+		{
+			CallerInfo{
+				FuncName: "Foo()",
+				File:     "formatter_test.go",
+				Line:     228,
+			},
+			"at Foo()(formatter_test.go:228)",
+		},
+		{
+			CallerInfo{
+				FuncName: "Bar()",
+				File:     "formatter.go",
+				Line:     123,
+			},
+			"at Bar()(formatter.go:123)",
+		},
+		{
+			CallerInfo{
+				FuncName: "Buzz()",
+				File:     "file.go",
+				Line:     5,
+			},
+			"at Buzz()(file.go:5)",
+		},
+	}
+
+	for _, tc := range cases {
+		fl := &AssertionFailure{
+			Stacktrace: []CallerInfo{tc.callerInfo},
+		}
+		fd := df.buildFormatData(ctx, fl)
+		assert.Equal(t, []string{tc.want}, fd.Stacktrace)
+	}
+}