Fix install non-.exe executables on Windows

spec/integration/install_spec.cr

@@ -836,13 +836,28 @@ describe "install" do
     foobar = File.join(application_path, "bin", Shards::Helpers.exe("foobar"))
     baz = File.join(application_path, "bin", Shards::Helpers.exe("baz"))
     foo = File.join(application_path, "bin", Shards::Helpers.exe("foo"))
+    crystal = File.join(application_path, "bin", "crystal.cr")
 
     File.exists?(foobar).should be_true # "Expected to have installed bin/foobar executable"
     File.exists?(baz).should be_true    # "Expected to have installed bin/baz executable"
     File.exists?(foo).should be_false   # "Expected not to have installed bin/foo executable"
+    File.exists?(crystal).should be_true
 
     `#{Process.quote(foobar)}`.should eq("OK")
     `#{Process.quote(baz)}`.should eq("KO")
+    File.read(crystal).should eq %(puts "crystal")
+  end
+
+  it "errors on missing executable" do
+    metadata = {
+      dependencies: {"executable_missing": "*"},
+    }
+    with_shard(metadata) do
+      ex = expect_raises(FailedCommand) { run "shards install --no-color" }
+      ex.stdout.should contain <<-ERROR
+        E: Could not find executable "nonexistent"
+        ERROR
+    end
   end
 
   it "skips installing executables" do

spec/integration/spec_helper.cr

@@ -127,10 +127,14 @@ private def setup_repositories
   create_git_repository "binary"
   create_executable "binary", "bin/foobar", %(print "OK")
   create_executable "binary", "bin/baz", %(print "KO")
-  create_git_release "binary", "0.1.0", {executables: ["foobar", "baz"]}
+  create_file "binary", "bin/crystal.cr", %(puts "crystal")
+  create_git_release "binary", "0.1.0", {executables: ["foobar", "baz", "crystal.cr"]}
   create_executable "binary", "bin/foo", %(print "FOO")
   create_git_release "binary", "0.2.0", {executables: ["foobar", "baz", "foo"]}
 
+  create_git_repository "executable_missing"
+  create_git_release "executable_missing", "0.1.0", {executables: ["nonexistent"]}
+
   create_git_repository "c"
   create_git_release "c", "0.1.0", {dependencies: {d: {git: git_url(:d), version: "0.1.0"}}}
   create_git_release "c", "0.2.0", {dependencies: {d: {git: git_url(:d), version: "0.2.0"}}}

src/package.cr

@@ -106,10 +106,13 @@ module Shards
       Dir.mkdir_p(Shards.bin_path)
 
       spec.executables.each do |name|
-        exe_name = Shards::Helpers.exe(name)
-        Log.debug { "Install bin/#{exe_name}" }
-        source = File.join(install_path, "bin", exe_name)
-        destination = File.join(Shards.bin_path, exe_name)
+        exe_name = find_executable_file(Path[install_path], name)
+        unless exe_name
+          raise Shards::Error.new("Could not find executable #{name.inspect}")
+        end
+        Log.debug { "Install #{exe_name}" }
+        source = File.join(install_path, exe_name)
+        destination = File.join(Shards.bin_path, File.basename(exe_name))
 
         if File.exists?(destination)
           next if File.same?(destination, source)
@@ -124,6 +127,18 @@ module Shards
       end
     end
 
+    def find_executable_file(install_path, name)
+      each_executable_path(name) do |path|
+        return path if File.exists?(install_path.join(path))
+      end
+    end
+
+    private def each_executable_path(name)
+      exe = Shards::Helpers.exe(name)
+      yield Path["bin", exe]
+      yield Path["bin", name] unless name == exe
+    end
+
     def to_yaml(builder)
       Dependency.new(name, resolver, version).to_yaml(builder)
     end