Respect a user's PYTHON or npm_config_python settings

bin/apm

@@ -28,10 +28,26 @@ binDir=`pwd -P`
 maybe_node_gyp_path="$binDir"/../node_modules/.bin/node-gyp
 if [ -e "$maybe_node_gyp_path" ]
 then
+  # Prevent vars like NODE_CONFIG_NODE_GYP from messing this up
+  for var in $(env | grep -i ^npm_config_node_gyp=)
+  do
+    unset ${var%%=*}
+  done
+
   export npm_config_node_gyp="$maybe_node_gyp_path"
 fi
 
-export PYTHON="${binDir}/python-interceptor.sh"
+export ATOM_APM_ORIGINAL_PYTHON="${PYTHON:-}"
+
+# Assumption: env iterates through environment variables in the same order that
+# process.env iterates through properties within npm. So, we take the last match.
+for var in $(env | grep -i ^npm_config_python=)
+do
+  ATOM_APM_ORIGINAL_PYTHON="${var#*=}"
+  unset ${var%%=*}
+done
+
+export npm_config_python="${SCRIPT_DIR}/python-interceptor.sh"
 
 builtin cd "$initialCwd"
 "$binDir/$nodeBin" "$binDir/../lib/cli.js" "$@"

bin/npm

@@ -2,11 +2,30 @@
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 export PATH="$SCRIPT_DIR:$PATH"
 
-export PYTHON="${SCRIPT_DIR}/python-interceptor.sh"
+export ATOM_APM_ORIGINAL_PYTHON="${PYTHON:-}"
+
+# Assumption: env iterates through environment variables in the same order that
+# process.env iterates through properties within npm. So, we take the last match.
+for var in $(env | grep -i ^npm_config_python=)
+do
+  ATOM_APM_ORIGINAL_PYTHON="${var#*=}"
+done
+if [ -z "${ATOM_APM_ORIGINAL_PYTHON}" ] && [ -n "${PYTHON:-}" ]
+then
+  ATOM_APM_ORIGINAL_PYTHON="${PYTHON}"
+fi
+
+export npm_config_python="${SCRIPT_DIR}/python-interceptor.sh"
 
 maybe_node_gyp_path="$SCRIPT_DIR"/../node_modules/.bin/node-gyp
 if [ -e "$maybe_node_gyp_path" ]
 then
+  # Prevent vars like NODE_CONFIG_NODE_GYP from messing this up
+  for var in $(env | grep -i ^npm_config_node_gyp=)
+  do
+    unset ${var%%=*}
+  done
+
   export npm_config_node_gyp="$maybe_node_gyp_path"
 fi
 

spec/fixtures/fake-python-1.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+echo "fake-python-1 called" >&2
+exit 1

spec/fixtures/fake-python-2.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+echo "fake-python-2 called" >&2
+exit 1

spec/install-spec.coffee

@@ -498,3 +498,46 @@ describe 'apm install', ->
 
           makefileContent = fs.readFileSync(path.join(testModuleDirectory, 'build', 'Makefile'), {encoding: 'utf-8'})
           expect(makefileContent).toMatch('node_modules/with\\ a\\ space/addon.gypi')
+
+    describe "configurable Python binaries", ->
+      nodeModules = fs.realpathSync(path.join(__dirname, '..', 'node_modules'))
+      [originalPython, originalNpmConfigPython] = []
+
+      beforeEach ->
+        originalPython = process.env.PYTHON
+        originalNpmConfigPython = process.env.npm_config_python
+        delete process.env.PYTHON
+        delete process.env.npm_config_python
+
+      afterEach ->
+        process.env.PYTHON = originalPython
+        process.env.npm_config_python = originalNpmConfigPython
+
+      it 'respects ${PYTHON} if set', ->
+        process.env.PYTHON = path.join __dirname, 'fixtures', 'fake-python-1.sh'
+
+        callback = jasmine.createSpy('callback')
+        apm.run(['install', 'native-package'], callback)
+
+        waitsFor 'waiting for install to fail', 600000, ->
+          callback.callCount is 1
+
+        runs ->
+          errorText = callback.mostRecentCall.args[0]
+          expect(errorText).not.toBeNull()
+          expect(errorText).toMatch('fake-python-1 called')
+
+      it 'respects ${npm_config_python} if set', ->
+        process.env.npm_config_python = path.join __dirname, 'fixtures', 'fake-python-2.sh'
+        process.env.PYTHON = path.join __dirname, 'fixtures', 'fake-python-1.sh'
+
+        callback = jasmine.createSpy('callback')
+        apm.run(['install', 'native-package'], callback)
+
+        waitsFor 'waiting for install to fail', 600000, ->
+          callback.callCount is 1
+
+        runs ->
+          errorText = callback.mostRecentCall.args[0]
+          expect(errorText).not.toBeNull()
+          expect(errorText).toMatch('fake-python-2 called')