Add bad data tests

Author: spiral-ladder

src/frame.zig

@@ -23,13 +23,13 @@ const IDENTIFIER_FRAME: [10]u8 = [_]u8{ 0xff, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61
 /// Max allowed size for an uncompressed payload according to the spec.
 const UNCOMPRESSED_CHUNK_SIZE_LIMIT = 65536;
 
-const UncompressError = error{
+pub const UncompressError = error{
     BadIdentifier,
     BadChecksum,
     IllegalChunkLength,
 } || snappy.Error || std.mem.Allocator.Error;
 
-const CompressError = std.mem.Allocator.Error || snappy.Error;
+pub const CompressError = std.mem.Allocator.Error || snappy.Error;
 
 /// Frame `bytes` into Snappy chunks, choosing compressed payloads only
 /// when they are smaller than their uncompressed counterparts.

src/snappy.zig

@@ -39,6 +39,28 @@ test "round trip - raw" {
     }
 }
 
+test "bad data" {
+    const allocator = std.testing.allocator;
+
+    var dir = try std.fs.cwd().openDir("testdata", .{ .iterate = true });
+    defer dir.close();
+
+    var it = dir.iterate();
+    while (try it.next()) |entry| {
+        if (entry.kind != .file) continue;
+        if (!std.mem.startsWith(u8, entry.name, "baddata")) continue;
+
+        var file = try dir.openFile(entry.name, .{});
+        defer file.close();
+
+        const bytes = try file.readToEndAlloc(allocator, std.math.maxInt(usize));
+        defer allocator.free(bytes);
+        const got = try allocator.alloc(u8, try raw.uncompressedLength(bytes));
+        defer allocator.free(got);
+        try std.testing.expectError(raw.Error.invalid_input, raw.uncompress(bytes[0..], got));
+    }
+}
+
 test "round trip - framed" {
     const allocator = std.testing.allocator;