export format property variables

format/format.go

@@ -36,6 +36,14 @@ var PrintContextObjects = false
 // TruncatedDiff choose if we should display a truncated pretty diff or not
 var TruncatedDiff = true
 
+// TruncateThreshold (default 50) specifies the maximum length string to print in string comparison assertion error
+// messages.
+var TruncateThreshold = 50
+
+// CharactersAroundMismatchToInclude (default 5) specifies how many contextual characters should be printed before and
+// after the first diff location in a truncated string assertion error message.
+var CharactersAroundMismatchToInclude = 5
+
 // Ctx interface defined here to keep backwards compatibility with go < 1.7
 // It matches the context.Context interface
 type Ctx interface {
@@ -88,7 +96,7 @@ to equal               |
 */
 
 func MessageWithDiff(actual, message, expected string) string {
-	if TruncatedDiff && len(actual) >= truncateThreshold && len(expected) >= truncateThreshold {
+	if TruncatedDiff && len(actual) >= TruncateThreshold && len(expected) >= TruncateThreshold {
 		diffPoint := findFirstMismatch(actual, expected)
 		formattedActual := truncateAndFormat(actual, diffPoint)
 		formattedExpected := truncateAndFormat(expected, diffPoint)
@@ -116,15 +124,15 @@ func truncateAndFormat(str string, index int) string {
 	leftPadding := `...`
 	rightPadding := `...`
 
-	start := index - charactersAroundMismatchToInclude
+	start := index - CharactersAroundMismatchToInclude
 	if start < 0 {
 		start = 0
 		leftPadding = ""
 	}
 
 	// slice index must include the mis-matched character
 	lengthOfMismatchedCharacter := 1
-	end := index + charactersAroundMismatchToInclude + lengthOfMismatchedCharacter
+	end := index + CharactersAroundMismatchToInclude + lengthOfMismatchedCharacter
 	if end > len(str) {
 		end = len(str)
 		rightPadding = ""
@@ -153,11 +161,6 @@ func findFirstMismatch(a, b string) int {
 	return 0
 }
 
-const (
-	truncateThreshold                 = 50
-	charactersAroundMismatchToInclude = 5
-)
-
 /*
 Pretty prints the passed in object at the passed in indentation level.
 

format/format_test.go

@@ -190,6 +190,38 @@ var _ = Describe("Format", func() {
 				Expect(MessageWithDiff(stringWithB, "to equal", stringWithZ)).Should(Equal(expectedFullFailureDiff))
 			})
 		})
+
+		Context("With alternate diff lengths", func() {
+			initialValue := TruncateThreshold // 5 by default
+			BeforeEach(func() {
+				TruncateThreshold = 10000
+			})
+
+			AfterEach(func() {
+				TruncateThreshold = initialValue
+			})
+			It("should show the full diff", func() {
+				stringWithB := "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+				stringWithZ := "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaazaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+
+				Expect(MessageWithDiff(stringWithB, "to equal", stringWithZ)).Should(Equal(expectedFullFailureDiff))
+			})
+		})
+
+		Context("With alternate diff lengths", func() {
+			It("long strings that differ only in length", func() {
+				smallString := "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+				largeString := "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+
+				Expect(MessageWithDiff(largeString, "to equal", smallString)).Should(Equal(expectedTruncatedStartSizeFailureMessage))
+				Expect(MessageWithDiff(smallString, "to equal", largeString)).Should(Equal(expectedTruncatedStartSizeSwappedFailureMessage))
+				initialValue := CharactersAroundMismatchToInclude // 5 by default
+				CharactersAroundMismatchToInclude = 10
+				Expect(MessageWithDiff(largeString, "to equal", smallString)).Should(Equal(expectedTruncatedStartSizeFailureMessageExtraDiff))
+				Expect(MessageWithDiff(smallString, "to equal", largeString)).Should(Equal(expectedTruncatedStartSizeSwappedFailureMessageExtraDiff))
+				CharactersAroundMismatchToInclude = initialValue
+			})
+		})
 	})
 
 	Describe("IndentString", func() {
@@ -613,12 +645,24 @@ Expected
 to equal               |
     <string>: "...aaaaa"
 `)
+var expectedTruncatedStartSizeFailureMessageExtraDiff = strings.TrimSpace(`
+Expected
+    <string>: "...aaaaaaaaaaa"
+to equal                    |
+    <string>: "...aaaaaaaaaa"
+`)
 var expectedTruncatedStartSizeSwappedFailureMessage = strings.TrimSpace(`
 Expected
     <string>: "...aaaa"
 to equal              |
     <string>: "...aaaaa"
 `)
+var expectedTruncatedStartSizeSwappedFailureMessageExtraDiff = strings.TrimSpace(`
+Expected
+    <string>: "...aaaaaaaaa"
+to equal                   |
+    <string>: "...aaaaaaaaaa"
+`)
 var expectedTruncatedMultiByteFailureMessage = strings.TrimSpace(`
 Expected
     <string>: "...tuvwxyz1"