test: Add server tests

This adds a way to test ocsigenserver using cram tests. This is
extremely valuable while developping a new feature and will help avoid
regressions in the future.

`server-test-helpers.sh` does the setup and teardown. Making a server
test is as simple as:

      $ source ../../server-test-helpers.sh
      $ run_server ./test.exe
      ... Server logs will appear here ...

      $ curl_ "index.html"

A first test is added that shows basic Staticmod and Deflatemod usage in `test/extensions/deflatemod.t`.

Author: Julow

test/dune

@@ -0,0 +1,7 @@
+(subdir
+ extensions
+ (cram
+  (package ocsigenserver)
+  (deps
+   ../server-test-helpers.sh
+   (package ocsigenserver))))

test/extensions/deflatemod.t/dune

@@ -0,0 +1,3 @@
+(executable
+ (name test)
+ (libraries ocsigenserver ocsigenserver.ext.staticmod ocsigenserver.ext.deflatemod))

test/extensions/deflatemod.t/dune-project

@@ -0,0 +1 @@
+(lang dune 3.18)

test/extensions/deflatemod.t/index.html

@@ -0,0 +1 @@
+Hello world

test/extensions/deflatemod.t/run.t

@@ -0,0 +1,43 @@
+  $ source ../../server-test-helpers.sh
+  $ run_server ./test.exe
+  ocsigen:main: [WARNING] Command pipe created
+  ocsigen:access:  connection for local-test from  (curl/8.12.1): /index.html
+  ocsigen:ext: [INFO] host found! local-test:0 matches .* 
+  ocsigen:ext:staticmod: [INFO] Is it a static file?
+  ocsigen:local-file: [INFO] Testing "./index.html".
+  ocsigen:local-file: [INFO] checking if file index.html can be sent
+  ocsigen:ext: [INFO] Compiling exclusion regexp $^
+  ocsigen:local-file: [INFO] Returning "./index.html".
+  ocsigen:access:  connection for local-test from  (curl/8.12.1): /index.html
+  ocsigen:ext: [INFO] host found! local-test:0 matches .* 
+  ocsigen:ext:staticmod: [INFO] Is it a static file?
+  ocsigen:local-file: [INFO] Testing "./index.html".
+  ocsigen:local-file: [INFO] checking if file index.html can be sent
+  ocsigen:local-file: [INFO] Returning "./index.html".
+  ocsigen:ext:deflate: [INFO] Zlib stream initialized
+  ocsigen:ext:deflate: [INFO] End of stream: big cleaning for zlib
+  ocsigen:ext:deflate: [INFO] Zlib.deflate finished, last flush
+  ocsigen:ext:deflate: [INFO] Flushing!
+  ocsigen:ext:deflate: [INFO] Zlib stream closed
+  application: [WARNING] Command received: shutdown
+
+First response is not compressed:
+
+  $ curl_ "index.html"
+  HTTP/1.1 200 OK
+  content-type: text/html
+  server: Ocsigen
+  content-length: 12
+  
+  Hello world
+
+Second response is compressed:
+
+  $ curl_ "index.html" --compressed
+  HTTP/1.1 200 OK
+  content-type: text/html
+  content-encoding: gzip
+  server: Ocsigen
+  transfer-encoding: chunked
+  
+  Hello world

test/extensions/deflatemod.t/test.ml

@@ -0,0 +1,12 @@
+let () =
+  Logs.Src.set_level Deflatemod.section (Some Logs.Debug);
+  Logs.set_level ~all:true (Some Logs.Debug);
+  Ocsigen_server.start
+    ~ports:[ (`File "./local.sock", 0) ]
+    ~veryverbose:() ~debugmode:true ~logdir:"log" ~datadir:"data"
+    ~uploaddir:None ~usedefaulthostname:true ~command_pipe:"local.cmd"
+    ~default_charset:(Some "utf-8")
+    [
+      Ocsigen_server.host
+        [ Staticmod.run ~dir:"." (); Deflatemod.run ~mode:(`All_but []) () ];
+    ]

test/server-test-helpers.sh

@@ -0,0 +1,42 @@
+# Bash functions that help test ocsigenserver
+
+# Run the server using 'dune exec -- "$@"' and doing the necessary setup.
+# The server must listen on the unix-domain socket named "local.sock" and on
+# the command-pipe named "local.cmd".
+#
+# Usage:
+#   $ run_server ./test.exe
+#   $ curl_ "index.html"
+#
+run_server ()
+{
+  mkdir -p log data # Directories that might be required by the server
+  dune build "$1"
+  # Run the server in the background, cut the datetime out of the log output.
+  dune exec -- "$@" 2>&1 | cut -d ' ' -f 4- &
+  # Wait for the unix-domain socket and the command-pipe to be created
+  local timeout=50 # Don't wait more than 0.5s
+  while ! ( [[ -e ./local.sock ]] && [[ -e ./local.cmd ]] ) && (( timeout-- > 0 )); do
+    sleep 0.01
+  done
+  # Print an error if a file is missing
+  ls ./local.sock ./local.cmd >/dev/null || return 1
+  # Shutdown the server at the end of the test
+  trap 'echo shutdown > local.cmd && wait' EXIT
+}
+
+# Wrapper around 'curl' that connects to the server. First argument is the
+# request path, the other arguments are directly passed to 'curl'.
+#
+# Usage:
+#   $ curl_ ""
+#   $ curl_ "index.html"
+#   $ curl_ "index.html" --no-show-headers   # Supress the headers
+#
+curl_ ()
+{
+  local path=$1; shift
+  # Remove the 'date' header, which is unreproducible
+  curl --unix-socket ./local.sock -s -i "$@" "http://local-test/$path" | \
+    grep -v "^date: "
+}