diff --git a/src/QuartoNotebookRunner.jl b/src/QuartoNotebookRunner.jl
index bdd578c..a25c13b 100644
--- a/src/QuartoNotebookRunner.jl
+++ b/src/QuartoNotebookRunner.jl
@@ -45,6 +45,7 @@ include("WorkerSetup.jl")
 include("server.jl")
 include("socket.jl")
 include("worker.jl")
+include("utilities.jl")
 include("precompile.jl")
 
 end # module QuartoNotebookRunner
diff --git a/src/utilities.jl b/src/utilities.jl
new file mode 100644
index 0000000..c3d4afe
--- /dev/null
+++ b/src/utilities.jl
@@ -0,0 +1,109 @@
+"""
+    test_pr(cmd::Cmd; url::String, rev::String)
+
+Test a PR by running the given command with the PR's changes. `url` defaults to
+the `QuartoNotebookRunner.jl` repo. `rev` is required, and should be the branch
+name of the PR. `cmd` should be the `quarto render` command to run.
+"""
+function test_pr(
+    cmd::Cmd;
+    url::String = "https://github.com/PumasAI/QuartoNotebookRunner.jl",
+    rev::String,
+)
+    # Require the user to already have a `quarto` install on their path.
+    quarto = Sys.which("quarto")
+    if isnothing(quarto)
+        error("Quarto not found. Please install Quarto.")
+    end
+
+    # We require at least v1.5.29 to run this backend.
+    version = VersionNumber(readchomp(`quarto --version`))
+    if version < v"1.5.29"
+        error(
+            "Quarto version $version is not supported. Please upgrade to at least v1.5.29.",
+        )
+    end
+
+    # Ensure that any running server is stopped before we start.
+    _stop_running_server() || error("Failed to stop the running server.")
+
+    mktempdir() do dir
+        file = joinpath(dir, "file.jl")
+        write(
+            file,
+            """
+            import Pkg
+            Pkg.add(; url = $(repr(url)), rev = $(repr(rev)))
+            """,
+        )
+        run(`$(Base.julia_cmd()) --startup-file=no --project=$dir $file`)
+        run(addenv(`$cmd --execute-debug`, "QUARTO_JULIA_PROJECT" => dir))
+    end
+end
+
+function _stop_running_server()
+    cache_dir = _quarto_julia_cache_dir()
+    transport_file = joinpath(cache_dir, "julia_transport.txt")
+    if isfile(transport_file)
+        @info "Removing transport file." transport_file
+
+        json = open(JSON3.read, transport_file)
+        pid = get(json, "pid", nothing)
+        try
+            _kill_proc(pid)
+        catch error
+            @error "Failed to stop the running server." error transport_file pid
+            return false
+        end
+        try
+            rm(transport_file)
+        catch error
+            @error "Failed to remove the transport file." error transport_file
+            return false
+        end
+    else
+        @info "No transport file found."
+    end
+    return true
+end
+
+function _kill_proc(id::Integer)
+    if Sys.iswindows()
+        run(`taskkill /F /PID $id`)
+    else
+        run(`kill -9 $id`)
+    end
+end
+
+function _quarto_julia_cache_dir()
+    home = homedir()
+    if Sys.isapple()
+        path = joinpath(home, "Library", "Caches", "quarto", "julia")
+        isdir(path) && return path
+    elseif Sys.iswindows()
+        localappdata = get(ENV, "LOCALAPPDATA", nothing)
+        if !isnothing(localappdata)
+            path = joinpath(localappdata, "quarto", "julia")
+            isdir(path) && return path
+        end
+
+        appdata = get(ENV, "APPDATA", nothing)
+        if !isnothing(appdata)
+            path = joinpath(appdata, "quarto", "julia")
+            isdir(path) && return path
+        end
+    elseif Sys.islinux()
+        xdg_cache_home = get(ENV, "XDG_CACHE_HOME", nothing)
+        if !isnothing(xdg_cache_home)
+            path = joinpath(xdg_cache_home, ".cache", "quarto", "julia")
+            isdir(path) && return path
+        end
+
+        path = joinpath(home, ".cache", "quarto", "julia")
+        isdir(path) && return path
+    else
+        error("Unsupported OS.")
+    end
+
+    error("Could not find a suitable cache directory.")
+end