From a9cf9fffe4b7ac6ed9f58d69e06f75681715a0e2 Mon Sep 17 00:00:00 2001
From: Ben Klein <robobenklein@gmail.com>
Date: Fri, 23 Feb 2018 16:56:19 -0500
Subject: [PATCH 1/2] Implement conditional linking

---
 README.md               |  1 +
 dotbot/plugins/link.py  | 18 ++++++++++++++++++
 test/tests/link-if.bash |  2 ++
 3 files changed, 21 insertions(+)
 create mode 100644 test/tests/link-if.bash

diff --git a/README.md b/README.md
index 1e5a5fe..759647e 100644
--- a/README.md
+++ b/README.md
@@ -192,6 +192,7 @@ Available extended configuration parameters:
 | `force` | Force removes the old target, file or folder, and forces a new link (default:false) |
 | `relative` | Use a relative path when creating the symlink (default:false, absolute links) |
 | `glob` | Treat a `*` character as a wildcard, and perform link operations on all of those matches (default:false) |
+| `if` | Execute this in your `$SHELL` and only link if it is successful. |
 
 #### Example
 
diff --git a/dotbot/plugins/link.py b/dotbot/plugins/link.py
index 5274e3b..bf1c5a9 100644
--- a/dotbot/plugins/link.py
+++ b/dotbot/plugins/link.py
@@ -2,6 +2,7 @@ import os
 import glob
 import shutil
 import dotbot
+import subprocess
 
 
 class Link(dotbot.Plugin):
@@ -31,6 +32,10 @@ class Link(dotbot.Plugin):
             use_glob = defaults.get('glob', False)
             if isinstance(source, dict):
                 # extended config
+                test = source.get('if')
+                if test is not None and not self._test_success(test):
+                    self._log.lowinfo('Skipping %s' % destination)
+                    continue
                 relative = source.get('relative', relative)
                 force = source.get('force', force)
                 relink = source.get('relink', relink)
@@ -90,6 +95,19 @@ class Link(dotbot.Plugin):
             self._log.error('Some links were not successfully set up')
         return success
 
+    def _test_success(self, command):
+        with open(os.devnull, 'w') as devnull:
+            ret = subprocess.call(
+                command,
+                shell=True,
+                stdout=devnull,
+                stderr=devnull,
+                executable=os.environ.get('SHELL'),
+            )
+        if ret != 0:
+            self._log.debug('Test \'%s\' returned false' % command)
+        return ret == 0
+
     def _default_source(self, destination, source):
         if source is None:
             basename = os.path.basename(destination)
diff --git a/test/tests/link-if.bash b/test/tests/link-if.bash
new file mode 100644
index 0000000..de7948f
--- /dev/null
+++ b/test/tests/link-if.bash
@@ -0,0 +1,2 @@
+test_description='link if'
+. '../test-lib.bash'

From b0ce63904c98a0f3f6547dc0d770aad22b08a8ef Mon Sep 17 00:00:00 2001
From: Anish Athalye <me@anishathalye.com>
Date: Tue, 16 Oct 2018 20:22:50 -0400
Subject: [PATCH 2/2] Add test for conditional linking

---
 test/tests/link-if.bash | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/test/tests/link-if.bash b/test/tests/link-if.bash
index de7948f..9fe6429 100644
--- a/test/tests/link-if.bash
+++ b/test/tests/link-if.bash
@@ -1,2 +1,32 @@
 test_description='link if'
 . '../test-lib.bash'
+
+test_expect_success 'setup' '
+mkdir ~/d
+echo "apple" > ${DOTFILES}/f
+'
+
+test_expect_success 'run' '
+run_dotbot <<EOF
+- link:
+    ~/.f:
+        path: f
+        if: "true"
+    ~/.g:
+        path: f
+        if: "false"
+    ~/.h:
+        path: f
+        if: "[[ -d ~/d ]]"
+    ~/.i:
+        path: f
+        if: "badcommand"
+EOF
+'
+
+test_expect_success 'test' '
+grep "apple" ~/.f &&
+! test -f ~/.g &&
+grep "apple" ~/.h &&
+! test -f ~/.i
+'