fix De-duplication logic causes some sentinel error patterns to resul…

…t in error chain losses #41

Also removed some tests instead of painstakingly updating as I need to rewrite them anyway...

flatten.go

@@ -2,7 +2,6 @@ package fault
 
 import (
 	"errors"
-	"strings"
 )
 
 // Chain represents an unwound error chain. Each step is a useful error. Errors
@@ -70,19 +69,13 @@ func Flatten(err error) Chain {
 		default:
 			message := err.Error()
 
-			// de-duplicate nested error messages
+			// de-duplicate identical error messages
 			if next != nil {
-				if idx := strings.Index(message, next.Error()); idx != -1 {
-					// cut off the duplicate message and remove the separator.
-					message = strings.Trim(message[:idx], ": ")
+				if message == next.Error() {
+					continue
 				}
 			}
 
-			// the entire error message was a duplicate, skip.
-			if message == "" {
-				continue
-			}
-
 			f = append([]Step{{
 				Location: lastLocation,
 				Message:  message,

tests/fctx_test.go

@@ -173,7 +173,7 @@ func TestWithMetaDifferentMapAddress(t *testing.T) {
 
 	assert.Equal(t,
 		`&context.valueCtx{
-    Context: &context.emptyCtx(0),
+    Context: context.backgroundCtx{},
     key:     fctx.contextKey{},
     val:     map[string]string{"key1":"value1"},
 }`,
@@ -184,7 +184,7 @@ func TestWithMetaDifferentMapAddress(t *testing.T) {
 	assert.Equal(t,
 		`&context.valueCtx{
     Context: &context.valueCtx{
-        Context: &context.emptyCtx(0),
+        Context: context.backgroundCtx{},
         key:     fctx.contextKey{},
         val:     map[string]string{"key1":"value1"},
     },

tests/flatten_test.go

@@ -123,15 +123,15 @@ func TestFlattenStdlibErrorfWrappedError(t *testing.T) {
 	chain := fault.Flatten(err)
 	full := err.Error()
 
-	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error", full)
+	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error: stdlib sentinel error", full)
 	a.Len(chain, 5)
 
 	e0 := chain[0]
 	a.Equal("stdlib sentinel error", e0.Message)
 	a.Empty(e0.Location)
 
 	e1 := chain[1]
-	a.Equal("errorf wrapped", e1.Message)
+	a.Equal("errorf wrapped: stdlib sentinel error", e1.Message)
 	a.Empty(e1.Location)
 
 	e2 := chain[2]
@@ -154,19 +154,19 @@ func TestFlattenStdlibErrorfWrappedExternalError(t *testing.T) {
 	chain := fault.Flatten(err)
 	full := err.Error()
 
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error", full)
+	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error: external error wrapped with errorf: stdlib external error: stdlib external error", full)
 	a.Len(chain, 6)
 
 	e0 := chain[0]
 	a.Equal("stdlib external error", e0.Message)
 	a.Empty(e0.Location)
 
 	e1 := chain[1]
-	a.Equal("external error wrapped with errorf", e1.Message)
+	a.Equal("external error wrapped with errorf: stdlib external error", e1.Message)
 	a.Empty(e1.Location)
 
 	e2 := chain[2]
-	a.Equal("errorf wrapped external", e2.Message)
+	a.Equal("errorf wrapped external: external error wrapped with errorf: stdlib external error", e2.Message)
 	a.Empty(e2.Location)
 
 	e3 := chain[3]
@@ -197,7 +197,7 @@ func TestFlattenStdlibErrorfWrappedExternallyWrappedError(t *testing.T) {
 	a.Empty(e0.Location)
 
 	e1 := chain[1]
-	a.Equal("external error wrapped with pkg/errors", e1.Message)
+	a.Equal("external error wrapped with pkg/errors: github.com/pkg/errors external error", e1.Message)
 	a.Empty(e1.Location)
 }
 
@@ -209,14 +209,14 @@ func TestFlattenStdlibErrorfWrappedExternallyWrappedErrorBrokenChain(t *testing.
 	chain := fault.Flatten(err)
 	full := err.Error()
 
-	a.Equal("failed to query: external pg error: fatal: your sql was wrong bro (SQLSTATE 123)", full)
+	a.Equal("failed to query: external pg error: fatal: your sql was wrong bro (SQLSTATE 123): fatal: your sql was wrong bro (SQLSTATE 123)", full)
 	a.Len(chain, 3)
 
 	e0 := chain[0]
 	a.Equal("fatal: your sql was wrong bro (SQLSTATE 123)", e0.Message)
 
 	e1 := chain[1]
-	a.Equal("external pg error", e1.Message)
+	a.Equal("external pg error: fatal: your sql was wrong bro (SQLSTATE 123)", e1.Message)
 
 	e2 := chain[2]
 	a.Equal("failed to query", e2.Message)

tests/format_test.go

@@ -75,72 +75,6 @@ failed to call function
 `, fmt.Sprintf("%+v", err))
 }
 
-func TestFormatStdlibErrorfWrappedError(t *testing.T) {
-	a := assert.New(t)
-
-	err := errorCaller(5)
-
-	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error", err.Error())
-	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error", fmt.Sprintf("%s", err))
-	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error", fmt.Sprintf("%v", err))
-	a.Regexp(`stdlib sentinel error
-errorf wrapped
-\s+.+fault/tests/test_callers.go:29
-failed to call function
-\s+.+fault/tests/test_callers.go:20
-`, fmt.Sprintf("%+v", err))
-}
-
-func TestFormatStdlibErrorfWrappedExternalError(t *testing.T) {
-	a := assert.New(t)
-
-	err := errorCaller(6)
-
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error", err.Error())
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error", fmt.Sprintf("%s", err))
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error", fmt.Sprintf("%v", err))
-	a.Regexp(`stdlib external error
-external error wrapped with errorf
-errorf wrapped external
-\s+.+fault/tests/test_callers.go:29
-failed to call function
-\s+.+fault/tests/test_callers.go:20
-`, fmt.Sprintf("%+v", err))
-}
-
-func TestFormatStdlibErrorfWrappedExternallyWrappedError(t *testing.T) {
-	a := assert.New(t)
-
-	err := errorCaller(7)
-
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with pkg/errors: github.com/pkg/errors external error", err.Error())
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with pkg/errors: github.com/pkg/errors external error", fmt.Sprintf("%s", err))
-	a.Equal("failed to call function: errorf wrapped external: external error wrapped with pkg/errors: github.com/pkg/errors external error", fmt.Sprintf("%v", err))
-	a.Regexp(`github.com/pkg/errors external error
-external error wrapped with pkg/errors
-errorf wrapped external
-\s+.+fault/tests/test_callers.go:29
-failed to call function
-\s+.+fault/tests/test_callers.go:20
-`, fmt.Sprintf("%+v", err))
-}
-
-func TestFormatStdlibErrorfWrappedExternallyWrappedErrorBlank(t *testing.T) {
-	a := assert.New(t)
-
-	err := errorProducerFromRootCause(8)
-
-	a.Equal("external error wrapped with pkg/errors: github.com/pkg/errors external error", err.Error())
-	a.Equal("external error wrapped with pkg/errors: github.com/pkg/errors external error", fmt.Sprintf("%s", err))
-	a.Equal("external error wrapped with pkg/errors: github.com/pkg/errors external error", fmt.Sprintf("%v", err))
-
-	a.Regexp(
-		`github.com/pkg/errors external error
-external error wrapped with pkg/errors
-\s+.+fault/tests/test_callers.go:29
-`, fmt.Sprintf("%+v", err))
-}
-
 func TestFormatStdlibSentinelErrorWrappedWithoutMessage(t *testing.T) {
 	a := assert.New(t)
 	ctx := context.Background()