Merge pull request #364 from nmiyake/fixFailOutput

Ensure that assert.Fail properly align its output

assert/assertions.go

@@ -153,7 +153,7 @@ func getWhitespaceString() string {
 	parts := strings.Split(file, "/")
 	file = parts[len(parts)-1]
 
-	return strings.Repeat(" ", len(fmt.Sprintf("%s:%d:      ", file, line)))
+	return strings.Repeat(" ", len(fmt.Sprintf("%s:%d:        ", file, line)))
 
 }
 
@@ -170,22 +170,18 @@ func messageFromMsgAndArgs(msgAndArgs ...interface{}) string {
 	return ""
 }
 
-// Indents all lines of the message by appending a number of tabs to each line, in an output format compatible with Go's
-// test printing (see inner comment for specifics)
-func indentMessageLines(message string, tabs int) string {
+// Aligns the provided message so that all lines after the first line start at the same location as the first line.
+// Assumes that the first line starts at the correct location (after carriage return, tab, label, spacer and tab).
+// The longestLabelLen parameter specifies the length of the longest label in the output (required becaues this is the
+// basis on which the alignment occurs).
+func indentMessageLines(message string, longestLabelLen int) string {
 	outBuf := new(bytes.Buffer)
 
 	for i, scanner := 0, bufio.NewScanner(strings.NewReader(message)); scanner.Scan(); i++ {
+		// no need to align first line because it starts at the correct location (after the label)
 		if i != 0 {
-			outBuf.WriteRune('\n')
-		}
-		for ii := 0; ii < tabs; ii++ {
-			outBuf.WriteRune('\t')
-			// Bizarrely, all lines except the first need one fewer tabs prepended, so deliberately advance the counter
-			// by 1 prematurely.
-			if ii == 0 && i > 0 {
-				ii++
-			}
+			// append alignLen+1 spaces to align with "{{longestLabel}}:" before adding tab
+			outBuf.WriteString("\n\r\t" + strings.Repeat(" ", longestLabelLen +1) + "\t")
 		}
 		outBuf.WriteString(scanner.Text())
 	}
@@ -217,29 +213,49 @@ func FailNow(t TestingT, failureMessage string, msgAndArgs ...interface{}) bool
 
 // Fail reports a failure through
 func Fail(t TestingT, failureMessage string, msgAndArgs ...interface{}) bool {
-
-	message := messageFromMsgAndArgs(msgAndArgs...)
-
-	errorTrace := strings.Join(CallerInfo(), "\n\r\t\t\t")
-	if len(message) > 0 {
-		t.Errorf("\r%s\r\tError Trace:\t%s\n"+
-			"\r\tError:%s\n"+
-			"\r\tMessages:\t%s\n\r",
-			getWhitespaceString(),
-			errorTrace,
-			indentMessageLines(failureMessage, 2),
-			message)
-	} else {
-		t.Errorf("\r%s\r\tError Trace:\t%s\n"+
-			"\r\tError:%s\n\r",
-			getWhitespaceString(),
-			errorTrace,
-			indentMessageLines(failureMessage, 2))
+	content := []labeledContent{
+		{"Error Trace", strings.Join(CallerInfo(), "\n\r\t\t\t")},
+		{"Error", failureMessage},
 	}
 
+	message := messageFromMsgAndArgs(msgAndArgs...)
+	if len(message) > 0 {
+		content = append(content, labeledContent{"Messages", message})
+	}
+
+	t.Errorf("\r" + getWhitespaceString() + labeledOutput(content...))
+
 	return false
 }
 
+type labeledContent struct {
+	label string
+	content string
+}
+
+// labeledOutput returns a string consisting of the provided labeledContent. Each labeled output is appended in the following manner:
+//
+//   \r\t{{label}}:{{align_spaces}}\t{{content}}\n
+//
+// The initial carriage return is required to undo/erase any padding added by testing.T.Errorf. The "\t{{label}}:" is for the label.
+// If a label is shorter than the longest label provided, padding spaces are added to make all the labels match in length. Once this
+// alignment is achieved, "\t{{content}}\n" is added for the output.
+//
+// If the content of the labeledOutput contains line breaks, the subsequent lines are aligned so that they start at the same location as the first line.
+func labeledOutput(content ...labeledContent) string {
+	longestLabel := 0
+	for _, v := range content {
+		if len(v.label) > longestLabel {
+			longestLabel = len(v.label)
+		}
+	}
+	var output string
+	for _, v := range content {
+		output += "\r\t" + v.label + ":" + strings.Repeat(" ", longestLabel-len(v.label)) + "\t" + indentMessageLines(v.content, longestLabel) + "\n"
+	}
+	return output
+}
+
 // Implements asserts that an object is implemented by the specified interface.
 //
 //    assert.Implements(t, (*MyInterface)(nil), new(MyObject), "MyObject")

assert/assertions_test.go

@@ -1,12 +1,16 @@
 package assert
 
 import (
+	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"math"
 	"os"
 	"reflect"
 	"regexp"
+	"runtime"
+	"strings"
 	"testing"
 	"time"
 )
@@ -197,6 +201,64 @@ func TestEqual(t *testing.T) {
 	}
 }
 
+// bufferT implements TestingT. Its implementation of Errorf writes the output that would be produced by
+// testing.T.Errorf to an internal bytes.Buffer.
+type bufferT struct {
+	buf bytes.Buffer
+}
+
+func (t *bufferT) Errorf(format string, args ...interface{}) {
+	// implementation of decorate is copied from testing.T
+	decorate := func(s string) string {
+		_, file, line, ok := runtime.Caller(3) // decorate + log + public function.
+		if ok {
+			// Truncate file name at last file name separator.
+			if index := strings.LastIndex(file, "/"); index >= 0 {
+				file = file[index+1:]
+			} else if index = strings.LastIndex(file, "\\"); index >= 0 {
+				file = file[index+1:]
+			}
+		} else {
+			file = "???"
+			line = 1
+		}
+		buf := new(bytes.Buffer)
+		// Every line is indented at least one tab.
+		buf.WriteByte('\t')
+		fmt.Fprintf(buf, "%s:%d: ", file, line)
+		lines := strings.Split(s, "\n")
+		if l := len(lines); l > 1 && lines[l-1] == "" {
+			lines = lines[:l-1]
+		}
+		for i, line := range lines {
+			if i > 0 {
+				// Second and subsequent lines are indented an extra tab.
+				buf.WriteString("\n\t\t")
+			}
+			buf.WriteString(line)
+		}
+		buf.WriteByte('\n')
+		return buf.String()
+	}
+	t.buf.WriteString(decorate(fmt.Sprintf(format, args...)))
+}
+
+func TestEqualFormatting(t *testing.T) {
+	for i, currCase := range []struct {
+		equalWant  string
+		equalGot   string
+		msgAndArgs []interface{}
+		want       string
+	}{
+		{equalWant:"want", equalGot: "got", want: "\tassertions.go:[0-9]+: \r                          \r\tError Trace:\t\n\t\t\r\tError:      \tNot equal: \n\t\t\r\t            \texpected: \"want\"\n\t\t\r\t            \treceived: \"got\"\n"},
+		{equalWant:"want", equalGot: "got", msgAndArgs: []interface{}{"hello, %v!", "world"}, want: "\tassertions.go:[0-9]+: \r                          \r\tError Trace:\t\n\t\t\r\tError:      \tNot equal: \n\t\t\r\t            \texpected: \"want\"\n\t\t\r\t            \treceived: \"got\"\n\t\t\r\tMessages:   \thello, world!\n"},
+	} {
+		mockT := &bufferT{}
+		Equal(mockT, currCase.equalWant, currCase.equalGot, currCase.msgAndArgs...)
+		Regexp(t, regexp.MustCompile(currCase.want), mockT.buf.String(), "Case %d", i)
+	}
+}
+
 func TestFormatUnequalValues(t *testing.T) {
 	expected, actual := formatUnequalValues("foo", "bar")
 	Equal(t, `"foo"`, expected, "value should not include type")