Touch install_path and lockfile to express dependency (#444)

* Touch install_path and lockfile to express dependency

* Write lockfile even when there are no dependencies

* Improve specs and implementation

Makefile

@@ -56,7 +56,6 @@ test_integration: bin/shards phony
 lib: shard.lock
 	mkdir -p lib/molinillo
 	$(SHARDS) install || (curl -L $(MOLINILLO_URL) | tar -xzf - -C lib/molinillo --strip-components=1)
-	touch lib
 
 shard.lock: shard.yml
 	$(SHARDS) update

spec/integration/install_spec.cr

@@ -1151,4 +1151,33 @@ describe "install" do
       stdout.should contain(%(Using --ignore-crystal-version was not needed. All shards are already compatible with Crystal 1.1.0))
     end
   end
+
+  describe "mtime" do
+    it "mtime lib > shard.lock > shard.yml" do
+      metadata = {dependencies: {
+        web: "*",
+      }}
+      with_shard(metadata) do
+        run "shards install"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+        run "shards install"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+      end
+    end
+
+    it "mtime shard.lock > shard.yml even when unmodified" do
+      metadata = {dependencies: {
+        web: "*",
+      }}
+      with_shard(metadata) do
+        run "shards install"
+        File.touch("shard.yml")
+        run "shards install"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+      end
+    end
+  end
 end

spec/integration/update_spec.cr

@@ -445,4 +445,33 @@ describe "update" do
       assert_locked "d", "0.2.0"
     end
   end
+
+  describe "mtime" do
+    it "mtime lib > shard.lock > shard.yml" do
+      metadata = {dependencies: {
+        web: "*",
+      }}
+      with_shard(metadata) do
+        run "shards update"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+        run "shards update"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+      end
+    end
+
+    it "mtime shard.lock > shard.yml even when unmodified" do
+      metadata = {dependencies: {
+        web: "*",
+      }}
+      with_shard(metadata) do
+        run "shards update"
+        File.touch("shard.yml")
+        run "shards update"
+        File.info("shard.lock").modification_time.should be <= File.info("lib").modification_time
+        File.info("shard.yml").modification_time.should be <= File.info("shard.lock").modification_time
+      end
+    end
+  end
 end

src/commands/install.cr

@@ -26,8 +26,14 @@ module Shards
 
         if generate_lockfile?(packages)
           write_lockfile(packages)
+        elsif !Shards.production?
+          # Touch lockfile so its mtime is bigger than that of shard.yml
+          File.touch(lockfile_path)
         end
 
+        # Touch install path so its mtime is bigger than that of the lockfile
+        File.touch(Shards.install_path)
+
         if ignore_crystal_version
           check_ignored_crystal_version(packages)
         end

src/commands/update.cr

@@ -22,8 +22,14 @@ module Shards
 
         if generate_lockfile?(packages)
           write_lockfile(packages)
+        else
+          # Touch lockfile so its mtime is bigger than that of shard.yml
+          File.touch(lockfile_path)
         end
 
+        # Touch install path so its mtime is bigger than that of the lockfile
+        File.touch(Shards.install_path)
+
         if ignore_crystal_version
           check_ignored_crystal_version(packages)
         end