testutil: Improved trimming when output is too large. (#5)

Now e.g.  Equals will print maximum of 1000 chars for each "exp", "act", "msg" and "diff", instead of 10k overall.

Printing more is still cluttering and impossible to debug by humans.

This allows to at least read beginnings of diff and each act and exp lines.

Signed-off-by: bwplotka <[email protected]>

Signed-off-by: bwplotka <[email protected]>

testutil/testutil.go

@@ -17,6 +17,16 @@ import (
 	"github.com/google/go-cmp/cmp"
 )
 
+const limitOfElemChars = 1e3
+
+func withLimitf(f string, v ...interface{}) string {
+	s := fmt.Sprintf(f, v...)
+	if len(s) > limitOfElemChars {
+		return s[:limitOfElemChars] + "...(output trimmed)"
+	}
+	return s
+}
+
 // Assert fails the test if the condition is false.
 func Assert(tb testing.TB, condition bool, v ...interface{}) {
 	tb.Helper()
@@ -29,7 +39,7 @@ func Assert(tb testing.TB, condition bool, v ...interface{}) {
 	if len(v) > 0 {
 		msg = fmt.Sprintf(v[0].(string), v[1:]...)
 	}
-	tb.Fatalf("\033[31m%s:%d: "+msg+"\033[39m\n\n", filepath.Base(file), line)
+	tb.Fatalf("\033[31m%s:%d: \"%s\"\033[39m\n\n", filepath.Base(file), line, withLimitf(msg))
 }
 
 // Ok fails the test if an err is not nil.
@@ -44,7 +54,7 @@ func Ok(tb testing.TB, err error, v ...interface{}) {
 	if len(v) > 0 {
 		msg = fmt.Sprintf(v[0].(string), v[1:]...)
 	}
-	tb.Fatalf("\033[31m%s:%d:"+msg+"\n\n unexpected error: %s\033[39m\n\n", filepath.Base(file), line, err.Error())
+	tb.Fatalf("\033[31m%s:%d: \"%s\"\n\n unexpected error: %s\033[39m\n\n", filepath.Base(file), line, withLimitf(msg), withLimitf(err.Error()))
 }
 
 // NotOk fails the test if an err is nil.
@@ -59,7 +69,7 @@ func NotOk(tb testing.TB, err error, v ...interface{}) {
 	if len(v) > 0 {
 		msg = fmt.Sprintf(v[0].(string), v[1:]...)
 	}
-	tb.Fatalf("\033[31m%s:%d:"+msg+"\n\n expected error, got nothing \033[39m\n\n", filepath.Base(file), line)
+	tb.Fatalf("\033[31m%s:%d: \"%s\"\n\n expected error, got nothing \033[39m\n\n", filepath.Base(file), line, withLimitf(msg))
 }
 
 // Equals fails the test if exp is not equal to act.
@@ -68,13 +78,20 @@ func Equals(tb testing.TB, exp, act interface{}, v ...interface{}) {
 	if reflect.DeepEqual(exp, act) {
 		return
 	}
-	_, file, line, _ := runtime.Caller(1)
+	fatalNotEqual(tb, exp, act, v...)
+}
+
+func fatalNotEqual(tb testing.TB, exp, act interface{}, v ...interface{}) {
+	_, file, line, _ := runtime.Caller(2)
 
 	var msg string
 	if len(v) > 0 {
 		msg = fmt.Sprintf(v[0].(string), v[1:]...)
 	}
-	tb.Fatal(sprintfWithLimit("\033[31m%s:%d:"+msg+"\n\n\texp: %#v\n\n\tgot: %#v%s\033[39m\n\n", filepath.Base(file), line, exp, act, diff(exp, act)))
+	tb.Fatalf(
+		"\033[31m%s:%d: \"%s\"\n\n\texp: %s\n\n\tgot: %s%s\033[39m\n\n",
+		filepath.Base(file), line, withLimitf(msg), withLimitf("%#v", exp), withLimitf("%#v", act), withLimitf(diff(exp, act)),
+	)
 }
 
 type goCmp struct {
@@ -83,7 +100,7 @@ type goCmp struct {
 
 // WithGoCmp allows specifying options and using https://github.com/google/go-cmp
 // for equality comparisons. The compatibility guarantee of this function's arguments
-// are the same as go-cmp i.e none due to v0.x.
+// are the same as go-cmp (no guarantee due to v0.x).
 func WithGoCmp(opts ...cmp.Option) goCmp {
 	return goCmp{opts: opts}
 }
@@ -95,13 +112,7 @@ func (o goCmp) Equals(tb testing.TB, exp, act interface{}, v ...interface{}) {
 	if cmp.Equal(exp, act, o.opts) {
 		return
 	}
-	_, file, line, _ := runtime.Caller(1)
-
-	var msg string
-	if len(v) > 0 {
-		msg = fmt.Sprintf(v[0].(string), v[1:]...)
-	}
-	tb.Fatal(sprintfWithLimit("\033[31m%s:%d:"+msg+"\n\n\texp: %#v\n\n\tgot: %#v%s\033[39m\n\n", filepath.Base(file), line, exp, act, diff(exp, act)))
+	fatalNotEqual(tb, exp, act, v...)
 }
 
 // FaultOrPanicToErr returns error if panic of fault was triggered during execution of function.
@@ -126,7 +137,7 @@ func ContainsStringSlice(tb testing.TB, haystack, needle []string) {
 	_, file, line, _ := runtime.Caller(1)
 
 	if !contains(haystack, needle) {
-		tb.Fatalf(sprintfWithLimit("\033[31m%s:%d: %#v does not contain %#v\033[39m\n\n", filepath.Base(file), line, haystack, needle))
+		tb.Fatalf("\033[31m%s:%d: %s does not contain %s\033[39m\n\n", filepath.Base(file), line, withLimitf("%#v", haystack), withLimitf("%#v", needle))
 	}
 }
 
@@ -166,14 +177,6 @@ func contains(haystack, needle []string) bool {
 	return false
 }
 
-func sprintfWithLimit(act string, v ...interface{}) string {
-	s := fmt.Sprintf(act, v...)
-	if len(s) > 10000 {
-		return s[:10000] + "...(output trimmed)"
-	}
-	return s
-}
-
 func typeAndKind(v interface{}) (reflect.Type, reflect.Kind) {
 	t := reflect.TypeOf(v)
 	k := t.Kind()