fix: issue 28 wrong location of some errors

.gitignore

@@ -1 +1 @@
-     .idea
+.idea/

fault.go

@@ -21,6 +21,17 @@ func Wrap(err error, w ...Wrapper) error {
 		return nil
 	}
 
+	// the passed err might already have a location if it's a fault.New error, or it might not if it's another type of
+	// error like one from the standard library. Wrapping it in a container with an empty location ensures that the
+	// location will be reset when we flatten the error chain. If the error is a fault.New error, it will itself be
+	// wrapped in a container which will have a location
+	if _, ok := err.(*container); !ok {
+		err = &container{
+			cause:    err,
+			location: "",
+		}
+	}
+
 	for _, fn := range w {
 		err = fn(err)
 	}

flatten.go

@@ -49,6 +49,14 @@ func Flatten(err error) Chain {
 		// exist to contain other errors that actually contain information,
 		// store the container's recorded location for usage with the next item.
 		case *container:
+			if _, ok := next.(*container); ok && unwrapped.location != "" {
+				// Having 2 containers back to back can happen if we're using .Wrap without using any wrappers. In that
+				// case, we add a Step to avoid losing the location whe the wrapping occurred
+				f = append([]Step{{
+					Location: unwrapped.location,
+					Message:  "",
+				}}, f...)
+			}
 			lastLocation = unwrapped.location
 
 		case *fundamental:
@@ -79,8 +87,6 @@ func Flatten(err error) Chain {
 				Location: lastLocation,
 				Message:  message,
 			}}, f...)
-
-			lastLocation = ""
 		}
 	}
 

tests/flatten_test.go

@@ -16,15 +16,23 @@ func TestFlattenStdlibSentinelError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: stdlib sentinel error", full)
-	a.Len(chain, 2)
+	a.Len(chain, 4)
 
 	e0 := chain[0]
 	a.Equal("stdlib sentinel error", e0.Message)
-	a.Contains(e0.Location, "test_callers.go:29")
+	a.Empty(e0.Location)
 
 	e1 := chain[1]
-	a.Equal("failed to call function", e1.Message)
-	a.Contains(e1.Location, "test_callers.go:20")
+	a.Empty(e1.Message)
+	a.Contains(e1.Location, "test_callers.go:29")
+
+	e2 := chain[2]
+	a.Equal("failed to call function", e2.Message)
+	a.Contains(e2.Location, "test_callers.go:20")
+
+	e3 := chain[3]
+	a.Empty(e3.Message)
+	a.Contains(e3.Location, "test_callers.go:11")
 }
 
 func TestFlattenFaultSentinelError(t *testing.T) {
@@ -35,15 +43,23 @@ func TestFlattenFaultSentinelError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: fault sentinel error", full)
-	a.Len(chain, 2)
+	a.Len(chain, 4)
 
 	e0 := chain[0]
 	a.Equal("fault sentinel error", e0.Message)
 	a.Contains(e0.Location, "root.go:15")
 
 	e1 := chain[1]
-	a.Equal("failed to call function", e1.Message)
-	a.Contains(e1.Location, "test_callers.go:20")
+	a.Empty(e1.Message)
+	a.Contains(e1.Location, "test_callers.go:29")
+
+	e2 := chain[2]
+	a.Equal("failed to call function", e2.Message)
+	a.Contains(e2.Location, "test_callers.go:20")
+
+	e3 := chain[3]
+	a.Empty(e3.Message)
+	a.Contains(e3.Location, "test_callers.go:11")
 }
 
 func TestFlattenStdlibInlineError(t *testing.T) {
@@ -54,15 +70,23 @@ func TestFlattenStdlibInlineError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: stdlib root cause error", full)
-	a.Len(chain, 2)
+	a.Len(chain, 4)
 
 	e0 := chain[0]
 	a.Equal("stdlib root cause error", e0.Message)
-	a.Contains(e0.Location, "test_callers.go:29")
+	a.Empty(e0.Location)
 
 	e1 := chain[1]
-	a.Equal("failed to call function", e1.Message)
-	a.Contains(e1.Location, "test_callers.go:20")
+	a.Empty(e1.Message)
+	a.Contains(e1.Location, "test_callers.go:29")
+
+	e2 := chain[2]
+	a.Equal("failed to call function", e2.Message)
+	a.Contains(e2.Location, "test_callers.go:20")
+
+	e3 := chain[3]
+	a.Empty(e3.Message)
+	a.Contains(e3.Location, "test_callers.go:11")
 }
 
 func TestFlattenFaultInlineError(t *testing.T) {
@@ -73,15 +97,23 @@ func TestFlattenFaultInlineError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: fault root cause error", full)
-	a.Len(chain, 2)
+	a.Len(chain, 4)
 
 	e0 := chain[0]
 	a.Equal("fault root cause error", e0.Message)
 	a.Contains(e0.Location, "root.go:28")
 
 	e1 := chain[1]
-	a.Equal("failed to call function", e1.Message)
-	a.Contains(e1.Location, "test_callers.go:20")
+	a.Empty(e1.Message)
+	a.Contains(e1.Location, "test_callers.go:29")
+
+	e2 := chain[2]
+	a.Equal("failed to call function", e2.Message)
+	a.Contains(e2.Location, "test_callers.go:20")
+
+	e3 := chain[3]
+	a.Empty(e3.Message)
+	a.Contains(e3.Location, "test_callers.go:11")
 }
 
 func TestFlattenStdlibErrorfWrappedError(t *testing.T) {
@@ -92,19 +124,27 @@ func TestFlattenStdlibErrorfWrappedError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: errorf wrapped: stdlib sentinel error", full)
-	a.Len(chain, 3)
+	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.Contains(e1.Location, "test_callers.go:29")
+	a.Empty(e1.Location)
 
 	e2 := chain[2]
-	a.Equal("failed to call function", e2.Message)
-	a.Contains(e2.Location, "test_callers.go:20")
+	a.Empty(e2.Message)
+	a.Contains(e2.Location, "test_callers.go:29")
+
+	e3 := chain[3]
+	a.Equal("failed to call function", e3.Message)
+	a.Contains(e3.Location, "test_callers.go:20")
+
+	e4 := chain[4]
+	a.Empty(e4.Message)
+	a.Contains(e4.Location, "test_callers.go:11")
 }
 
 func TestFlattenStdlibErrorfWrappedExternalError(t *testing.T) {
@@ -115,7 +155,7 @@ func TestFlattenStdlibErrorfWrappedExternalError(t *testing.T) {
 	full := err.Error()
 
 	a.Equal("failed to call function: errorf wrapped external: external error wrapped with errorf: stdlib external error", full)
-	a.Len(chain, 4)
+	a.Len(chain, 6)
 
 	e0 := chain[0]
 	a.Equal("stdlib external error", e0.Message)
@@ -127,11 +167,19 @@ func TestFlattenStdlibErrorfWrappedExternalError(t *testing.T) {
 
 	e2 := chain[2]
 	a.Equal("errorf wrapped external", e2.Message)
-	a.Contains(e2.Location, "test_callers.go:29")
+	a.Empty(e2.Location)
 
 	e3 := chain[3]
-	a.Equal("failed to call function", e3.Message)
-	a.Contains(e3.Location, "test_callers.go:20")
+	a.Empty(e3.Message)
+	a.Contains(e3.Location, "test_callers.go:29")
+
+	e4 := chain[4]
+	a.Equal("failed to call function", e4.Message)
+	a.Contains(e4.Location, "test_callers.go:20")
+
+	e5 := chain[5]
+	a.Empty(e5.Message)
+	a.Contains(e5.Location, "test_callers.go:11")
 }
 
 func TestFlattenStdlibErrorfWrappedExternallyWrappedError(t *testing.T) {

tests/format_test.go

@@ -36,8 +36,10 @@ func TestFormatFaultSentinelError(t *testing.T) {
 	a.Equal("failed to call function: fault sentinel error", fmt.Sprintf("%v", err))
 	a.Regexp(`fault sentinel error
 \s+.+fault/tests/root.go:15
+\s+.+fault/tests/test_callers.go:29
 failed to call function
 \s+.+fault/tests/test_callers.go:20
+\s+.+fault/tests/test_callers.go:11
 `, fmt.Sprintf("%+v", err))
 }
 
@@ -66,8 +68,10 @@ func TestFormatFaultInlineError(t *testing.T) {
 	a.Equal("failed to call function: fault root cause error", fmt.Sprintf("%v", err))
 	a.Regexp(`fault root cause error
 \s+.+fault/tests/root.go:28
+\s+.+fault/tests/test_callers.go:29
 failed to call function
 \s+.+fault/tests/test_callers.go:20
+\s+.+fault/tests/test_callers.go:11
 `, fmt.Sprintf("%+v", err))
 }