Add tmp::file::read method (#18)

Implement tmp::file::read method, which returns the ifstream for the file

include/tmp/file

@@ -3,6 +3,7 @@
 #include <tmp/path>
 
 #include <filesystem>
+#include <fstream>
 #include <string_view>
 
 namespace tmp {
@@ -57,6 +58,10 @@ public:
     /// @throws std::filesystem::filesystem_error if cannot create a file
     static file text(std::string_view prefix = "");
 
+    /// Reads the contents of this file
+    /// @returns A file stream with this file contents
+    std::ifstream read() const;
+
     /// Writes the given content to this file discarding any previous content
     /// @param content  A string to write to this file
     void write(std::string_view content) const;

lib/file.cpp

@@ -53,6 +53,13 @@ file file::text(std::string_view prefix) {
     return file(prefix, /*binary=*/false);
 }
 
+std::ifstream file::read() const {
+    const fs::path& file = *this;
+    return binary
+        ? std::ifstream(file, std::ios::binary)
+        : std::ifstream(file);
+}
+
 void file::write(std::string_view content) const {
     stream(*this, binary, /*append=*/false) << content;
 }

tests/file_test.cpp

@@ -90,6 +90,17 @@ TEST(FileTest, MoveAssignment) {
     ASSERT_EQ(fs::path(fst), path2);
 }
 
+TEST(FileTest, Read) {
+    const auto tmpfile = tmp::file(PREFIX);
+    tmpfile.write("Hello");
+    tmpfile.append(", world!");
+
+    auto stream = tmpfile.read();
+
+    auto content = std::string(std::istreambuf_iterator<char>(stream), {});
+    ASSERT_EQ(content, "Hello, world!");
+}
+
 TEST(FileTest, Write) {
     const auto tmpfile = tmp::file(PREFIX);
     tmpfile.write("Hello");