Added support for specifying compression in tests

Refactored tests code to allow to specify compression (content-encoding) algorithm.

Added tests to verify what actix actually handle different content encodings properly.

meilisearch-http/tests/common/encoder.rs

@@ -0,0 +1,50 @@
+use std::io::Write;
+use actix_http::header::TryIntoHeaderPair;
+use bytes::Bytes;
+use flate2::write::{GzEncoder, ZlibEncoder};
+use flate2::Compression;
+
+#[derive(Clone,Copy)]
+pub enum Encoder {
+    Plain,
+    Gzip,
+    Deflate,
+    Brotli,
+}
+
+impl Encoder {
+    pub fn encode(self: &Encoder, body: impl Into<Bytes>) -> impl Into<Bytes> {
+        match self {
+            Self::Gzip => {
+                let mut encoder = GzEncoder::new(Vec::new(), Compression::default());
+                encoder.write_all(&body.into()).expect("Failed to encode request body");
+                encoder.finish().expect("Failed to encode request body")
+            }
+            Self::Deflate => {
+                let mut encoder = ZlibEncoder::new(Vec::new(), Compression::default());
+                encoder.write_all(&body.into()).expect("Failed to encode request body");
+                encoder.finish().unwrap()
+            }
+            Self::Plain => Vec::from(body.into()),
+            Self::Brotli => {
+                let mut encoder = brotli::CompressorWriter::new(Vec::new(), 32 * 1024, 3, 22);
+                encoder.write_all(&body.into()).expect("Failed to encode request body");
+                encoder.flush().expect("Failed to encode request body");
+                encoder.into_inner()
+            }
+        }
+    }
+
+    pub fn header(self: &Encoder) -> Option<impl TryIntoHeaderPair> {
+        match self {
+            Self::Plain => None,
+            Self::Gzip => Some(("Content-Encoding", "gzip")),
+            Self::Deflate => Some(("Content-Encoding", "deflate")),
+            Self::Brotli => Some(("Content-Encoding", "br")),
+        }
+    }
+
+    pub fn iterator() -> impl Iterator<Item = Self> {
+        [Self::Plain, Self::Gzip, Self::Deflate, Self::Brotli].iter().copied()
+    }
+}