Add some tests, and add a configurable soak test

backend/Cargo.lock

@@ -1,5 +1,14 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "aho-corasick"
+version = "0.7.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e37cfd5e7657ada45f742d6e99ca5788580b5c529dc78faf11ece6dc702656f"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "ansi_term"
 version = "0.11.0"
@@ -1319,6 +1328,8 @@ version = "1.5.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d07a8629359eb56f1e2fb1652bb04212c072a87ba68546a04065d525673ac461"
 dependencies = [
+ "aho-corasick",
+ "memchr",
  "regex-syntax",
 ]
 
@@ -1537,6 +1548,16 @@ dependencies = [
  "opaque-debug",
 ]
 
+[[package]]
+name = "shellwords"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "89e515aa4699a88148ed5ef96413ceef0048ce95b43fbc955a33bde0a70fcae6"
+dependencies = [
+ "lazy_static",
+ "regex",
+]
+
 [[package]]
 name = "signal-hook-registry"
 version = "1.4.0"
@@ -1669,6 +1690,7 @@ dependencies = [
  "rustc-hash",
  "serde",
  "serde_json",
+ "shellwords",
  "simple_logger",
  "smallvec",
  "soketto",