Add --version option

CHANGELOG.md

@@ -8,6 +8,8 @@ change log follows the conventions of
 
 ### Added
 
+- An option `--version` that prints the elle-cli version and exits.
+
 ### Changed
 
 - Report a proper error for an unknown model name (#100).

src/elle_cli/cli.clj

@@ -42,6 +42,13 @@
     h
     ))
 
+(defn version
+  "Return the elle-cli version from the pom.properties embedded by
+  Leiningen at build time."
+  []
+  (when-let [r (io/resource "META-INF/maven/elle-cli/elle-cli/pom.properties")]
+    (second (re-find #"(?m)^version=(.*)$" (slurp r)))))
+
 (defn vl
   [v]
   (if (string? v)
@@ -109,6 +116,8 @@
     :validate [#{:text :json} "Must be one of text, json"]]
    ["-h" "--help"
     "(General) Print usage."]
+   [nil "--version"
+    "(General) Print version and exit."]
 
    ; Elle-specific options.
    ["-c" "--consistency-models CONSISTENCY-MODELS"
@@ -231,6 +240,10 @@
           (println e))
         (System/exit 1))
 
+      (when (:version options)
+        (println (str "elle-cli " (version)))
+        (System/exit 0))
+
       (if (or (nil? model-name) (true? help)) (
           (println (usage summary))
           (System/exit 0)))

test/elle_cli/elle_cli_test.clj

@@ -7,6 +7,7 @@
             [clojure.java.io :as io]
             [clojure.data.json :as json]
             [jepsen.history :as h]
+            [clojure.tools.cli :as tools-cli]
             [elle_cli.cli :as cli]))
 
 (def data-dir
@@ -275,6 +276,16 @@
           (is (.exists expected)
               (str "generated expected result: " (.getPath expected)))))))
 
+(deftest check-version-option
+  (testing "--version is parsed without errors"
+    (let [{:keys [options errors]} (tools-cli/parse-opts ["--version"] cli/opts)]
+      (is (nil? errors))
+      (is (true? (:version options)))))
+  (testing "version is reported in the MAJOR.MINOR.PATCH format"
+    (let [v (cli/version)]
+      (is (some? v))
+      (is (re-matches #"\d+\.\d+\.\d+" v)))))
+
 (deftest check-histories
   (doseq [[model cases] model-cases
           case cases]