test: write to tmp dir rather than fixture dir

test-fs-realpath.js was writing files to the fixture dir. This changes
it to use the temp directory instead. This also replaces some of the
string concatenation for paths with uses of path.join() and
path.relative().

PR-URL: nodejs#4489
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

test/parallel/test-fs-realpath.js

@@ -37,11 +37,14 @@ function tmp(p) {
   return path.join(common.tmpDir, p);
 }
 
-var fixturesAbsDir = common.fixturesDir;
+var targetsAbsDir = path.join(common.tmpDir, 'targets');
 var tmpAbsDir = common.tmpDir;
-assert(fixturesAbsDir !== tmpAbsDir);
 
-console.error('absolutes\n%s\n%s', fixturesAbsDir, tmpAbsDir);
+// Set up targetsAbsDir and expected subdirectories
+fs.mkdirSync(targetsAbsDir);
+fs.mkdirSync(path.join(targetsAbsDir, 'nested-index'));
+fs.mkdirSync(path.join(targetsAbsDir, 'nested-index', 'one'));
+fs.mkdirSync(path.join(targetsAbsDir, 'nested-index', 'two'));
 
 function asynctest(testBlock, args, callback, assertBlock) {
   async_expected++;
@@ -109,7 +112,7 @@ function test_simple_absolute_symlink(callback) {
   console.log('using type=%s', type);
 
   var entry = tmpAbsDir + '/symlink',
-      expected = fixturesAbsDir + '/nested-index/one';
+      expected = common.fixturesDir + '/nested-index/one';
   [
     [entry, expected]
   ].forEach(function(t) {
@@ -133,14 +136,15 @@ function test_deep_relative_file_symlink(callback) {
   }
 
   var expected = path.join(common.fixturesDir, 'cycles', 'root.js');
-  var linkData1 = '../../cycles/root.js';
-  var linkPath1 = path.join(common.fixturesDir,
+  var linkData1 = path.relative(path.join(targetsAbsDir, 'nested-index', 'one'),
+    expected);
+  var linkPath1 = path.join(targetsAbsDir,
                             'nested-index', 'one', 'symlink1.js');
   try {fs.unlinkSync(linkPath1);} catch (e) {}
   fs.symlinkSync(linkData1, linkPath1, 'file');
 
   var linkData2 = '../one/symlink1.js';
-  var entry = path.join(common.fixturesDir,
+  var entry = path.join(targetsAbsDir,
                         'nested-index', 'two', 'symlink1-b.js');
   try {fs.unlinkSync(entry);} catch (e) {}
   fs.symlinkSync(linkData2, entry, 'file');
@@ -160,14 +164,14 @@ function test_deep_relative_dir_symlink(callback) {
     return runNextTest();
   }
   var expected = path.join(common.fixturesDir, 'cycles', 'folder');
-  var linkData1b = '../../cycles/folder';
-  var linkPath1b = path.join(common.fixturesDir,
-                             'nested-index', 'one', 'symlink1-dir');
+  var path1b = path.join(targetsAbsDir, 'nested-index', 'one');
+  var linkPath1b = path.join(path1b, 'symlink1-dir');
+  var linkData1b = path.relative(path1b, expected);
   try {fs.unlinkSync(linkPath1b);} catch (e) {}
   fs.symlinkSync(linkData1b, linkPath1b, 'dir');
 
   var linkData2b = '../one/symlink1-dir';
-  var entry = path.join(common.fixturesDir,
+  var entry = path.join(targetsAbsDir,
                         'nested-index', 'two', 'symlink12-dir');
   try {fs.unlinkSync(entry);} catch (e) {}
   fs.symlinkSync(linkData2b, entry, 'dir');
@@ -276,11 +280,11 @@ function test_deep_symlink_mix(callback) {
   /tmp/node-test-realpath-d1 -> $tmpDir/node-test-realpath-d2
   /tmp/node-test-realpath-d2/foo -> $tmpDir/node-test-realpath-f2
   /tmp/node-test-realpath-f2
-    -> /node/test/fixtures/nested-index/one/realpath-c
-  /node/test/fixtures/nested-index/one/realpath-c
-    -> /node/test/fixtures/nested-index/two/realpath-c
-  /node/test/fixtures/nested-index/two/realpath-c -> $tmpDir/cycles/root.js
-  /node/test/fixtures/cycles/root.js (hard)
+    -> $tmpDir/targets/nested-index/one/realpath-c
+  $tmpDir/targets/nested-index/one/realpath-c
+    -> $tmpDir/targets/nested-index/two/realpath-c
+  $tmpDir/targets/nested-index/two/realpath-c -> $tmpDir/cycles/root.js
+  $tmpDir/targets/cycles/root.js (hard)
   */
   var entry = tmp('node-test-realpath-f1');
   try { fs.unlinkSync(tmp('node-test-realpath-d2/foo')); } catch (e) {}
@@ -292,11 +296,11 @@ function test_deep_symlink_mix(callback) {
       [tmp('node-test-realpath-d1'),
         common.tmpDir + '/node-test-realpath-d2'],
       [tmp('node-test-realpath-d2/foo'), '../node-test-realpath-f2'],
-      [tmp('node-test-realpath-f2'), fixturesAbsDir +
+      [tmp('node-test-realpath-f2'), targetsAbsDir +
         '/nested-index/one/realpath-c'],
-      [fixturesAbsDir + '/nested-index/one/realpath-c', fixturesAbsDir +
+      [targetsAbsDir + '/nested-index/one/realpath-c', targetsAbsDir +
         '/nested-index/two/realpath-c'],
-      [fixturesAbsDir + '/nested-index/two/realpath-c',
+      [targetsAbsDir + '/nested-index/two/realpath-c',
         common.tmpDir + '/cycles/root.js']
     ].forEach(function(t) {
       try { fs.unlinkSync(t[0]); } catch (e) {}