From d82b468cd5895e7c72bce72289522549f7225496 Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Thu, 21 Dec 2017 15:25:09 -0600
Subject: [PATCH 1/2] Invoke nix-build with single expression, nix-build
 handles this better

This results in much less memory usage, see issue for example.

Fixes #84.
---
 nox/review.py            | 7 +++----
 nox/tests/test_review.py | 5 +++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/nox/review.py b/nox/review.py
index 0d31db9..81fe333 100644
--- a/nox/review.py
+++ b/nox/review.py
@@ -15,10 +15,9 @@ def get_build_command(args, attrs, path):
     """ Get the appropriate command to use to build the given attributes """
     command = ['nix-build']
     command += args
-    for a in attrs:
-        command.append('-A')
-        command.append(a)
-    command.append(path)
+    command.append("-E")
+
+    command.append("with import %s {}; [ %s ]" % (path, ' '.join(attrs)))
     return command
 
 
diff --git a/nox/tests/test_review.py b/nox/tests/test_review.py
index b7f3042..0329c87 100644
--- a/nox/tests/test_review.py
+++ b/nox/tests/test_review.py
@@ -5,12 +5,13 @@
 
 class TestReview(unittest.TestCase):
     def test_get_build_command(self):
-        result = review.get_build_command([], ["nox"], ".")
-        self.assertEqual(["nix-build", "-A", "nox", "."], result)
+        result = review.get_build_command([], ["nox"], "./.")
+        self.assertEqual(["nix-build", "-E", "with import ./. {}; [ nox ]"], result)
 
     def test_build_in_path(self):
         # Just do a dry run to make sure there aren't any exceptions
         self.assertIs(None, review.build_in_path([], ["nox"], ".", dry_run=True))
+        self.assertIs(None, review.build_in_path([], ["nox"], "./.", dry_run=True))
 
     def test_differences(self):
         # Tuples of <old set>, <new set>, <expected difference>

From 9184555c954d571d896a5c6dfbfe5b783f7d3b24 Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Thu, 21 Dec 2017 15:51:55 -0600
Subject: [PATCH 2/2] Send attribute expression via stdin, fixes #73.

---
 nox/review.py            | 19 ++++++++++++++-----
 nox/tests/test_review.py |  8 ++++++--
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/nox/review.py b/nox/review.py
index 81fe333..8bd9375 100644
--- a/nox/review.py
+++ b/nox/review.py
@@ -11,16 +11,21 @@
 from .nixpkgs_repo import get_repo, packages, packages_for_sha
 
 
-def get_build_command(args, attrs, path):
+def get_build_command(args):
     """ Get the appropriate command to use to build the given attributes """
     command = ['nix-build']
     command += args
     command.append("-E")
+    command.append("-")
 
-    command.append("with import %s {}; [ %s ]" % (path, ' '.join(attrs)))
     return command
 
 
+def get_build_expr(attrs, path):
+    """ Get the appropriate expression to use to build the given attributes """
+    return "with import {} {{}}; [ {} ]".format(path, ' '.join(attrs))
+
+
 def build_in_path(args, attrs, path, dry_run=False):
     """Build the given package attributes in the given nixpkgs path"""
     if not attrs:
@@ -32,15 +37,19 @@ def build_in_path(args, attrs, path, dry_run=False):
     click.echo('Building in {}: {}'.format(click.style(result_dir, bold=True),
                                            click.style(' '.join(attrs), bold=True)))
 
-    command = get_build_command(args, attrs, canonical_path)
+    expr = get_build_expr(attrs, canonical_path)
+    command = get_build_command(args)
 
-    click.echo('Invoking {}'.format(' '.join(command)))
+    click.echo('Invoking {} with expression {}'.format(' '.join(command), expr))
 
     if dry_run:
         return
 
     try:
-        subprocess.check_call(command, cwd=result_dir)
+        with tempfile.SpooledTemporaryFile() as expr_f:
+            expr_f.write(expr.encode('utf-8'))
+            expr_f.seek(0)
+            subprocess.check_call(command, cwd=result_dir, stdin=expr_f)
     except subprocess.CalledProcessError:
         click.secho('The invocation of "{}" failed'.format(' '.join(command)), fg='red')
         sys.exit(1)
diff --git a/nox/tests/test_review.py b/nox/tests/test_review.py
index 0329c87..ccb7405 100644
--- a/nox/tests/test_review.py
+++ b/nox/tests/test_review.py
@@ -5,8 +5,12 @@
 
 class TestReview(unittest.TestCase):
     def test_get_build_command(self):
-        result = review.get_build_command([], ["nox"], "./.")
-        self.assertEqual(["nix-build", "-E", "with import ./. {}; [ nox ]"], result)
+        result = review.get_build_command([])
+        self.assertEqual(["nix-build", "-E", "-"], result)
+
+    def test_get_build_expr(self):
+        result = review.get_build_expr(["nox"], "./.")
+        self.assertEqual("with import ./. {}; [ nox ]", result)
 
     def test_build_in_path(self):
         # Just do a dry run to make sure there aren't any exceptions