Add Errorf and ErrnoErrorf
String formatting for error message can be done by using Errorf and
ErrnoErrorf. e.g. `return Errorf("{} failures", num_failure);`
The string format follows that of fmtlib, not printf.
Bug: 132145659
Test: libbase_test
Change-Id: I65f45d5f12ed23e2c14d6eb442278f467cc42e83
diff --git a/base/result_test.cpp b/base/result_test.cpp
index e864b97..2ee4057 100644
--- a/base/result_test.cpp
+++ b/base/result_test.cpp
@@ -355,5 +355,68 @@
EXPECT_EQ(old_errno, result2.error().code());
}
+TEST(result, error_with_fmt) {
+ Result<int> result = Errorf("{} {}!", "hello", "world");
+ EXPECT_EQ("hello world!", result.error().message());
+
+ result = Errorf("{} {}!", std::string("hello"), std::string("world"));
+ EXPECT_EQ("hello world!", result.error().message());
+
+ result = Errorf("{h} {w}!", fmt::arg("w", "world"), fmt::arg("h", "hello"));
+ EXPECT_EQ("hello world!", result.error().message());
+
+ result = Errorf("hello world!");
+ EXPECT_EQ("hello world!", result.error().message());
+
+ Result<int> result2 = Errorf("error occurred with {}", result.error());
+ EXPECT_EQ("error occurred with hello world!", result2.error().message());
+
+ constexpr int test_errno = 6;
+ errno = test_errno;
+ result = ErrnoErrorf("{} {}!", "hello", "world");
+ EXPECT_EQ(test_errno, result.error().code());
+ EXPECT_EQ("hello world!: "s + strerror(test_errno), result.error().message());
+}
+
+TEST(result, error_with_fmt_carries_errno) {
+ constexpr int inner_errno = 6;
+ errno = inner_errno;
+ Result<int> inner_result = ErrnoErrorf("inner failure");
+ errno = 0;
+ EXPECT_EQ(inner_errno, inner_result.error().code());
+
+ // outer_result is created with Errorf, but its error code is got from inner_result.
+ Result<int> outer_result = Errorf("outer failure caused by {}", inner_result.error());
+ EXPECT_EQ(inner_errno, outer_result.error().code());
+ EXPECT_EQ("outer failure caused by inner failure: "s + strerror(inner_errno),
+ outer_result.error().message());
+
+ // now both result objects are created with ErrnoErrorf. errno from the inner_result
+ // is not passed to outer_result.
+ constexpr int outer_errno = 10;
+ errno = outer_errno;
+ outer_result = ErrnoErrorf("outer failure caused by {}", inner_result.error());
+ EXPECT_EQ(outer_errno, outer_result.error().code());
+ EXPECT_EQ("outer failure caused by inner failure: "s + strerror(inner_errno) + ": "s +
+ strerror(outer_errno),
+ outer_result.error().message());
+}
+
+TEST(result, errno_chaining_multiple) {
+ constexpr int errno1 = 6;
+ errno = errno1;
+ Result<int> inner1 = ErrnoErrorf("error1");
+
+ constexpr int errno2 = 10;
+ errno = errno2;
+ Result<int> inner2 = ErrnoErrorf("error2");
+
+ // takes the error code of inner2 since its the last one.
+ Result<int> outer = Errorf("two errors: {}, {}", inner1.error(), inner2.error());
+ EXPECT_EQ(errno2, outer.error().code());
+ EXPECT_EQ("two errors: error1: "s + strerror(errno1) + ", error2: "s + strerror(errno2),
+ outer.error().message());
+}
+
} // namespace base
} // namespace android