Add tests for types with custom Error interface.

spew/common_test.go

@@ -58,6 +58,13 @@ func (p panicer) String() string {
 	panic("test panic")
 }
 
+// customError is used to test custom error interface invocation.
+type customError int
+
+func (e customError) Error() string {
+	return fmt.Sprintf("error: %d", int(e))
+}
+
 // stringizeWants converts a slice of wanted test output into a format suitable
 // for an test error message.
 func stringizeWants(wants []string) string {

spew/dump_test.go

@@ -734,6 +734,21 @@ func addPanicDumpTests() {
 	addDumpTest(nv, "(*"+vt+")(<nil>)\n")
 }
 
+func addErrorDumpTests() {
+	// Type that has a custom Error interface.
+	v := customError(127)
+	nv := (*customError)(nil)
+	pv := &v
+	vAddr := fmt.Sprintf("%p", pv)
+	pvAddr := fmt.Sprintf("%p", &pv)
+	vt := "spew_test.customError"
+	vs := "error: 127"
+	addDumpTest(v, "("+vt+") "+vs+"\n")
+	addDumpTest(pv, "(*"+vt+")("+vAddr+")("+vs+")\n")
+	addDumpTest(&pv, "(**"+vt+")("+pvAddr+"->"+vAddr+")("+vs+")\n")
+	addDumpTest(nv, "(*"+vt+")(<nil>)\n")
+}
+
 // TestDump executes all of the tests described by dumpTests.
 func TestDump(t *testing.T) {
 	// Setup tests.
@@ -754,6 +769,7 @@ func TestDump(t *testing.T) {
 	addFuncDumpTests()
 	addCircularDumpTests()
 	addPanicDumpTests()
+	addErrorDumpTests()
 
 	t.Logf("Running %d tests", len(dumpTests))
 	for i, test := range dumpTests {

spew/format_test.go

@@ -51,6 +51,7 @@ base test element are also tested to ensure proper indirection across all types.
 - Structs that are circular through cross referencing
 - Structs that are indirectly circular
 - Type that panics in its Stringer interface
+- Type that has a custom Error interface
 */
 
 package spew_test
@@ -1250,6 +1251,33 @@ func addPanicFormatterTests() {
 	addFormatterTest("%#+v", nv, "(*"+vt+")"+"<nil>")
 }
 
+func addErrorFormatterTests() {
+	// Type that has a custom Error interface.
+	v := customError(127)
+	nv := (*customError)(nil)
+	pv := &v
+	vAddr := fmt.Sprintf("%p", pv)
+	pvAddr := fmt.Sprintf("%p", &pv)
+	vt := "spew_test.customError"
+	vs := "error: 127"
+	addFormatterTest("%v", v, vs)
+	addFormatterTest("%v", pv, "<*>"+vs)
+	addFormatterTest("%v", &pv, "<**>"+vs)
+	addFormatterTest("%v", nv, "<nil>")
+	addFormatterTest("%+v", v, vs)
+	addFormatterTest("%+v", pv, "<*>("+vAddr+")"+vs)
+	addFormatterTest("%+v", &pv, "<**>("+pvAddr+"->"+vAddr+")"+vs)
+	addFormatterTest("%+v", nv, "<nil>")
+	addFormatterTest("%#v", v, "("+vt+")"+vs)
+	addFormatterTest("%#v", pv, "(*"+vt+")"+vs)
+	addFormatterTest("%#v", &pv, "(**"+vt+")"+vs)
+	addFormatterTest("%#v", nv, "(*"+vt+")"+"<nil>")
+	addFormatterTest("%#+v", v, "("+vt+")"+vs)
+	addFormatterTest("%#+v", pv, "(*"+vt+")("+vAddr+")"+vs)
+	addFormatterTest("%#+v", &pv, "(**"+vt+")("+pvAddr+"->"+vAddr+")"+vs)
+	addFormatterTest("%#+v", nv, "(*"+vt+")"+"<nil>")
+}
+
 // TestFormatter executes all of the tests described by formatterTests.
 func TestFormatter(t *testing.T) {
 	// Setup tests.
@@ -1270,6 +1298,7 @@ func TestFormatter(t *testing.T) {
 	addFuncFormatterTests()
 	addCircularFormatterTests()
 	addPanicFormatterTests()
+	addErrorFormatterTests()
 
 	t.Logf("Running %d tests", len(formatterTests))
 	for i, test := range formatterTests {