Add scoop-alias command

Fixes #377

lib/commands.ps1

@@ -20,8 +20,11 @@ function command_path($cmd) {
         # get path from shim
         $shim_path = "$scoopdir\shims\scoop-$cmd.ps1"
         $line = ((gc $shim_path) | where { $_.startswith('$path') })
-        iex -command "$line"
+        if($line) {
-        $cmd_path = $path
+            iex -command "$line"
+            $cmd_path = $path
+        }
+        else { $cmd_path = $shim_path }
     } 
 
     $cmd_path

libexec/scoop-alias.ps1

@@ -0,0 +1,89 @@
+# Usage: scoop alias add|list|rm [<args>]
+# Summary: Manage scoop aliases
+# Help: Add, remove or list Scoop aliases
+#
+# Aliases are custom Scoop subcommands that can be created to make common tasks
+# easier. 
+#
+# To add an Alias:
+#     scoop alias add <name> <command> <description>
+#
+# e.g.:
+#     scoop alias add rm 'scoop uninstall $args[0]' "Uninstalls an app"
+
+param($opt, $name, $command, $description)
+
+. "$psscriptroot\..\lib\core.ps1"
+. "$psscriptroot\..\lib\help.ps1"
+. "$psscriptroot\..\lib\config.ps1"
+. "$psscriptroot\..\lib\install.ps1"
+
+$script:config_alias = "alias"
+
+function init_alias_config {
+  $aliases = get_config $script:config_alias
+  if(!$aliases) {
+    $aliases = @{}
+  }
+
+  $aliases
+}
+
+function add_alias($name, $command) {
+  if(!$command) {
+    abort "can't create an empty alias"
+  }
+
+  # get current aliases from config
+  $aliases = init_alias_config
+  if($aliases.containskey($name)) {
+    abort "alias $name already exists"
+  }
+
+  $alias_file = "scoop-$name"
+
+  # generate script
+  $shimdir = shimdir $false
+  $script = 
+@"
+# Summary: $description
+$command
+"@
+  $script | out-file "$shimdir\$alias_file.ps1" -encoding oem
+
+  # add alias to config
+  $aliases += @{ $name = $alias_file }
+  set_config $script:config_alias $aliases
+}
+
+function rm_alias($name) {
+  $aliases = get_config $script:config_alias
+
+  if($aliases.containskey($name)) {
+    "removing alias $name..."
+
+    rm_shim $aliases.get_item($name) (shimdir $false)
+
+    $aliases.remove($name)
+    set_config $script:config_alias $aliases
+  }
+  else { abort "alias $name doesn't exist" }
+}
+
+function list_aliases {
+  $aliases = @{}
+  (get_config $script:config_alias).getenumerator() |% { 
+    $summary = summary (gc (command_path $_.name) -raw)
+    if(!($summary)) { $summary = '' }
+    $aliases.add("$($_.name) ", $summary)
+  }
+
+  $aliases.getenumerator() | sort name | ft -hidetablehead -autosize -wrap
+}
+
+switch($opt) {
+  "add" { add_alias $name $command }
+  "rm" { rm_alias $name }
+  "list" { list_aliases }
+  default { my_usage; exit 1 }
+}

test/Scoop-Alias.Tests.ps1

@@ -0,0 +1,59 @@
+. "$psscriptroot\..\libexec\scoop-alias.ps1"
+
+reset_aliases
+
+describe "add_alias" {
+  mock shimdir { "test\fixtures\shim" }
+  mock set_config { }
+  mock get_config { @{} }
+  $shimdir = shimdir
+
+  context "alias doesn't exist" {
+    it "creates a new alias" {
+      $alias_file = "$shimdir\scoop-rm.ps1"
+      $alias_file | should not exist
+
+      add_alias "rm" '"hello, world!"'
+      iex $alias_file | should be "hello, world!"
+    }
+  }
+
+  context "alias exists" {
+    it "does not change existing alias" {
+      $alias_file = "$shimdir\scoop-rm.ps1"
+      new-item $alias_file -type file
+      $alias_file | should exist
+
+      add_alias "rm" "test"
+      $alias_file | should contain ""
+    }
+  }
+
+  aftereach {
+    rm "test\fixtures\shim\scoop-rm.ps1" -ea ignore
+  }
+}
+
+describe "rm_alias" {
+  mock shimdir { "test\fixtures\shim" }
+  $shimdir = shimdir
+  mock set_config { }
+  mock get_config { @{} }
+
+  context "alias exists" {
+    it "removes an existing alias" {
+      $alias_file = "$shimdir\scoop-rm.ps1"
+      add_alias "rm" '"hello, world!"'
+
+      $alias_file | should exist
+      mock get_config { @(@{"rm" = "scoop-rm"}) }
+
+      rm_alias "rm"
+      $alias_file | should not exist
+    }
+  }
+
+  afterall {
+    rm "test\fixtures\shim\scoop-rm.ps1" -ea ignore
+  }
+}