add invoke tests

Signed-off-by: Mohammed Al Sahaf <msaa1990@gmail.com>

caddytest/spec/http/invoke/spec.hurl

@@ -0,0 +1,195 @@
+# Configure Caddy with invoke directive and a named route
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+}
+&(api) {
+	respond "API response"
+}
+localhost {
+	invoke api
+}
+```
+HTTP 200
+
+# invoke runs the named route inline
+GET https://localhost:9443/anything
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "API response"
+
+
+# Configure Caddy with invoke gated by a matcher
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+}
+&(api) {
+	respond "API: invoked"
+}
+localhost {
+	@api path /api/*
+	handle @api {
+		invoke api
+	}
+	respond "default"
+}
+```
+HTTP 200
+
+# matcher selects the invoke
+GET https://localhost:9443/api/foo
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "API: invoked"
+
+# non-matching path falls through to default handler
+GET https://localhost:9443/other
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "default"
+
+
+# Configure Caddy with multiple named routes invoked from different sites
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+}
+&(v1) {
+	respond "Version: v1"
+}
+&(v2) {
+	respond "Version: v2"
+}
+localhost {
+	@v1 path /v1/*
+	@v2 path /v2/*
+	handle @v1 {
+		invoke v1
+	}
+	handle @v2 {
+		invoke v2
+	}
+	respond "Version: unknown"
+}
+```
+HTTP 200
+
+# /v1/ invokes the v1 named route
+GET https://localhost:9443/v1/anything
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "Version: v1"
+
+# /v2/ invokes the v2 named route
+GET https://localhost:9443/v2/anything
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "Version: v2"
+
+# unmatched path falls back
+GET https://localhost:9443/
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "Version: unknown"
+
+
+# Configure Caddy with a non-terminal named route followed by a respond
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+}
+&(addheader) {
+	header X-Middleware "applied"
+}
+localhost {
+	invoke addheader
+	respond "Done"
+}
+```
+HTTP 200
+
+# invoke can run non-terminal handlers that mutate the response
+GET https://localhost:9443/test
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+header "X-Middleware" == "applied"
+body == "Done"
+
+
+# Configure Caddy with a named route used by both a route and a handle block
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+}
+&(echo) {
+	respond "echoed"
+}
+localhost {
+	@a path /route-style
+	@b path /handle-style
+	route @a {
+		invoke echo
+	}
+	handle @b {
+		invoke echo
+	}
+	respond "default"
+}
+```
+HTTP 200
+
+# invoke from inside route { }
+GET https://localhost:9443/route-style
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "echoed"
+
+# invoke from inside handle { }
+GET https://localhost:9443/handle-style
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+body == "echoed"