Support arbitrary objects in msgAndArgs

Author: viswajithiii

assert/assertions.go

@@ -179,7 +179,11 @@ func messageFromMsgAndArgs(msgAndArgs ...interface{}) string {
 		return ""
 	}
 	if len(msgAndArgs) == 1 {
-		return msgAndArgs[0].(string)
+		msg := msgAndArgs[0]
+		if msgAsStr, ok := msg.(string); ok {
+			return msgAsStr
+		}
+		return fmt.Sprintf("%+v", msg)
 	}
 	if len(msgAndArgs) > 1 {
 		return fmt.Sprintf(msgAndArgs[0].(string), msgAndArgs[1:]...)

assert/assertions_test.go

@@ -283,6 +283,8 @@ func TestEqualFormatting(t *testing.T) {
 	}{
 		{equalWant: "want", equalGot: "got", want: "\tassertions.go:\\d+: \n\t+Error Trace:\t\n\t+Error:\\s+Not equal:\\s+\n\\s+expected: \"want\"\n\\s+actual\\s+: \"got\"\n\\s+Diff:\n\\s+-+ Expected\n\\s+\\++ Actual\n\\s+@@ -1 \\+1 @@\n\\s+-want\n\\s+\\+got\n"},
 		{equalWant: "want", equalGot: "got", msgAndArgs: []interface{}{"hello, %v!", "world"}, want: "\tassertions.go:[0-9]+: \n\t+Error Trace:\t\n\t+Error:\\s+Not equal:\\s+\n\\s+expected: \"want\"\n\\s+actual\\s+: \"got\"\n\\s+Diff:\n\\s+-+ Expected\n\\s+\\++ Actual\n\\s+@@ -1 \\+1 @@\n\\s+-want\n\\s+\\+got\n\\s+Messages:\\s+hello, world!\n"},
+		{equalWant: "want", equalGot: "got", msgAndArgs: []interface{}{123}, want: "\tassertions.go:[0-9]+: \n\t+Error Trace:\t\n\t+Error:\\s+Not equal:\\s+\n\\s+expected: \"want\"\n\\s+actual\\s+: \"got\"\n\\s+Diff:\n\\s+-+ Expected\n\\s+\\++ Actual\n\\s+@@ -1 \\+1 @@\n\\s+-want\n\\s+\\+got\n\\s+Messages:\\s+123\n"},
+		{equalWant: "want", equalGot: "got", msgAndArgs: []interface{}{struct{a string}{"hello"}}, want: "\tassertions.go:[0-9]+: \n\t+Error Trace:\t\n\t+Error:\\s+Not equal:\\s+\n\\s+expected: \"want\"\n\\s+actual\\s+: \"got\"\n\\s+Diff:\n\\s+-+ Expected\n\\s+\\++ Actual\n\\s+@@ -1 \\+1 @@\n\\s+-want\n\\s+\\+got\n\\s+Messages:\\s+{a:hello}\n"},
 	} {
 		mockT := &bufferT{}
 		Equal(mockT, currCase.equalWant, currCase.equalGot, currCase.msgAndArgs...)