Clarify docs, add tests for transitive deps

This commit clarifies some things in the docs based on PR review.
It also adds additional test coverage for managed dependencies;
specifically, a case where two normal dependencies both have
a transitive dependency on the same library, but with different
versions.  The test validates that this conflict is properly
resolved via `:managed-dependencies`.

doc/MANAGED_DEPS.md

@@ -23,13 +23,14 @@ regular `:dependencies` section, with two exceptions:
 
 1. It does not actually introduce any dependencies to your project.  It only says,
   "hey leiningen, if you encounter one of these dependencies later, here are the
-  versions that you should use."
+  versions that you should fall back to if the version numbers aren't explicitly
+  specified."
 2. It allows the version number to be omitted from the `:dependencies` section,
   for any artifact that you've listed in your `:managed-dependencies` section.
 
 Here's an example:
 
-```clojure
+```clj
 (defproject superfun/happyslide "1.0.0-SNAPSHOT"
   :description "A Clojure project with managed dependencies"
   :min-lein-version  "2.7.0"
@@ -59,7 +60,7 @@ the [`lein-parent` plugin](https://github.com/achin/lein-parent).  This plugin
 will allow you to define a single "parent" project that is inherited by multiple
 "child" projects; e.g.:
 
-```
+```clj
 (defproject superfun/myparent "1.0.0"
    :managed-dependencies [[clj-time "0.12.0"]
                             [me.raynes/fs "1.4.6"]

test/leiningen/test/deps.clj

@@ -158,33 +158,48 @@
                       (:dependencies managed-deps-project)
                       (:managed-dependencies managed-deps-project)))
         ;; the list of deps from the managed deps section that aren't used
-        unused-managed-deps (remove
-                             (fn [dep]
-                               (some (partial coordinates-match? dep) merged-deps))
-                             managed-deps)
+        unused-managed-deps (-> (remove
+                                 (fn [dep]
+                                   (or (some (partial coordinates-match? dep) merged-deps)
+                                       ;; special-casing to remove tools.reader, which is a common transitive dep
+                                       ;; of two of our normal dependencies
+                                       (= 'org.clojure/tools.reader (first dep))))
+                                 managed-deps))
         ;; deps that have classifiers
         classified-deps (filter
                          #(some #{:classifier} %)
                          merged-deps)]
     ;; make sure the sample data has some unmanaged deps, some unused managed deps,
     ;; and some classified deps, for completeness
-    (is (not (empty? versioned-unmanaged-deps)))
-    (is (not (empty? unused-managed-deps)))
-    (is (not (empty? classified-deps)))
+    (is (seq versioned-unmanaged-deps))
+    (is (seq unused-managed-deps))
+    (is (seq classified-deps))
     ;; delete all of the existing artifacts for merged deps
     (doseq [[n v] merged-deps]
         (delete-file-recursively (m2-dir n v) :silently))
     ;; delete all of the artifacts for the managed deps too
     (doseq [[n v] managed-deps]
       (delete-file-recursively (m2-dir n v) :silently))
+    ;; delete all copies of tools.reader so we know that the managed dependency
+    ;; for it is taking precedence
+    (delete-file-recursively (m2-dir 'org.clojure/tools.reader) :silently)
     (deps managed-deps-project)
     ;; artifacts should be available for all merged deps
     (doseq [[n v] merged-deps]
-      (is (.exists (m2-dir n v)) (str n " was not downloaded.")))
+      (is (.exists (m2-dir n v)) (str n " was not downloaded (missing dir '" (m2-dir n v) "').")))
     ;; artifacts should *not* have been downloaded for unused managed deps
     (doseq [[n v] unused-managed-deps]
-      (is (not (.exists (m2-dir n v))) (str n " was unexpectedly downloaded.")))
+      (is (not (.exists (m2-dir n v))) (str n " was unexpectedly downloaded (found unexpected dir '" (m2-dir n v) "').")))
     ;; artifacts with classifiers should be available
     (doseq [[n v _ classifier] classified-deps]
       (let [f (m2-file n v classifier)]
-        (is (.exists f) (str f " was not downloaded."))))))
+        (is (.exists f) (str f " was not downloaded."))))
+    ;; check tools.reader explicitly, since it is our special transitive dependency
+    (let [tools-reader-versions (into [] (.listFiles (m2-dir 'org.clojure/tools.reader)))]
+      (is (= 1 (count tools-reader-versions)))
+      (is (= (first tools-reader-versions) (m2-dir 'org.clojure/tools.reader
+                                                   (->> managed-deps
+                                                        (filter
+                                                         (fn [dep] (= 'org.clojure/tools.reader (first dep))))
+                                                        first
+                                                        second)))))))

test/leiningen/test/helper.clj

@@ -2,7 +2,8 @@
   (:require [leiningen.core.project :as project]
             [leiningen.core.user :as user]
             [leiningen.core.test.helper :as helper]
-            [clojure.java.io :as io])
+            [clojure.java.io :as io]
+            [clojure.string :as str])
   (:import (java.io ByteArrayOutputStream PrintStream FileDescriptor
                     FileOutputStream)))
 
@@ -11,9 +12,13 @@
 
 (def tmp-dir (System/getProperty "java.io.tmpdir"))
 
-(defn m2-dir [n v]
-  (io/file local-repo
-           (if (string? n) n (or (namespace n) (name n))) (name n) v))
+(defn m2-dir
+  ([n]
+   (let [group (-> (if (string? n) n (or (namespace n) (name n)))
+                   (str/replace "." "/"))]
+     (io/file local-repo group (name n))))
+  ([n v]
+   (io/file (m2-dir n) v)))
 
 (defn m2-file [n v classifier]
   (io/file (m2-dir n v) (str (name n) "-" v "-" classifier ".jar")))

test_projects/managed-deps/project.clj

@@ -8,11 +8,15 @@
                  [ring/ring "1.0.0"]
                  [ring/ring-codec "1.0.1"]
                  [commons-math/commons-math "1.2" :classifier "sources"]
-                 [ring/ring-defaults "0.2.1"]]
+                 [ring/ring-defaults "0.2.1"]
+                 [org.clojure/tools.reader "1.0.0-beta3"]]
 
   :dependencies [[org.clojure/clojure]
                  [rome/rome nil]
                  [ring]
                  [ring/ring-codec nil :exclusions [commons-codec]]
                  [commons-codec "1.6"]
-                 [commons-math nil :classifier "sources"]])
+                 [commons-math nil :classifier "sources"]
+                 [org.clojure/tools.emitter.jvm "0.1.0-beta5"] ; depends on tools.reader 0.8.5
+                 [org.clojure/tools.namespace "0.3.0-alpha3"] ; depends on tools.reader 0.10.0
+                 ])