mix xref graph - add json support and related changes

lib/mix/test/mix/utils_test.exs

@@ -178,51 +178,56 @@ defmodule Mix.UtilsTest do
     end
   end
 
-  test "verify that write_according_to_opts/3 works as expected" do
-    # ignore any error from this call.
-
-    test_out = "test.out"
-    test_out_bak = "test.out.bak"
-    hello_world = "Hello World!"
-    new_hello_world = "New Hello World!"
-    default_out = "default.out"
-
-    # make sure none of the files exist - ignore errors
-    File.rm(test_out)
-    File.rm(test_out_bak)
-    File.rm(default_out)
-
-    # no optional override - write to the specified default file
-    assert Mix.Utils.write_according_to_opts!(test_out, [hello_world], []) == test_out
-    assert File.read!(test_out) == hello_world
-
-    # no optional override - write to the specified default file again, with old file backed up
-    assert Mix.Utils.write_according_to_opts!(test_out, [new_hello_world], []) == test_out
-    assert File.read!(test_out) == new_hello_world
-    assert File.read!(test_out_bak) == hello_world
-
-    # cleanup
-    File.rm!(test_out)
-    File.rm!(test_out_bak)
-
-    # with optional override - write to the specified default file
-    assert Mix.Utils.write_according_to_opts!(default_out, [hello_world], output: test_out) ==
-             test_out
-
-    assert File.read!(test_out) == hello_world
-
-    # with optional override - write to the specified default file again, with old file backed up
-    assert Mix.Utils.write_according_to_opts!(default_out, [new_hello_world], output: test_out) ==
-             test_out
+  describe "write_according_to_opts/3" do
+    test "verify that file writes with backups work as expected" do
+      test_out = "test.out"
+      test_out_bak = "test.out.bak"
+      hello_world = "Hello World!"
+      new_hello_world = "New Hello World!"
+      default_out = "default.out"
+
+      # ignore any error from this call.
+      in_tmp("write to default file", fn ->
+        # no optional override - write to the specified default file
+        assert Mix.Utils.write_according_to_opts!(test_out, [hello_world], []) == test_out
+        assert File.read!(test_out) == hello_world
+
+        # no optional override - write to the specified default file again, with old file backed up
+        assert Mix.Utils.write_according_to_opts!(test_out, [new_hello_world], []) == test_out
+        assert File.read!(test_out) == new_hello_world
+        assert File.read!(test_out_bak) == hello_world
+      end)
+
+      in_tmp("write to optional file override", fn ->
+        # with optional override - write to the specified default file
+        assert Mix.Utils.write_according_to_opts!(default_out, [hello_world], output: test_out) ==
+                 test_out
+
+        assert File.read!(test_out) == hello_world
+
+        # with optional override - write to the specified default file again, with old file backed up
+        assert Mix.Utils.write_according_to_opts!(default_out, [new_hello_world],
+                 output: test_out
+               ) ==
+                 test_out
+
+        assert File.read!(test_out) == new_hello_world
+        assert File.read!(test_out_bak) == hello_world
+      end)
+    end
 
-    assert File.read!(test_out) == new_hello_world
-    assert File.read!(test_out_bak) == hello_world
+    test "verify that writing to STDOUT works as expected" do
+      in_tmp("make sure we don't actually write to disk", fn ->
+        output =
+          ExUnit.CaptureIO.capture_io(fn ->
+            Mix.Utils.write_according_to_opts!("the_file.txt", ["some text"], output: "-")
+          end)
 
-    # cleanup again
-    File.rm!(test_out)
-    File.rm!(test_out_bak)
+        assert output == "some text"
 
-    # we don't test the handling of "-" here, we test it implicitly in xref_test.exs
+        assert File.exists?("the_file.txt") == false
+      end)
+    end
   end
 
   defp assert_ebin_symlinked_or_copied(result) do