command: Fix tests for "terraform fmt" command

Some underlying assumptions have shifted here, so although the behavior
is still broadly the same we need to accommodate some different details.

command/fmt_test.go

@@ -29,7 +29,7 @@ func TestFmt_errorReporting(t *testing.T) {
 		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
 	}
 
-	expected := fmt.Sprintf("Error running fmt: stat %s: no such file or directory", dummy_file)
+	expected := "There is no configuration directory at"
 	if actual := ui.ErrorWriter.String(); !strings.Contains(actual, expected) {
 		t.Fatalf("expected:\n%s\n\nto include: %q", actual, expected)
 	}
@@ -106,9 +106,14 @@ func TestFmt_directoryArg(t *testing.T) {
 		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
 	}
 
-	expected := fmt.Sprintf("%s\n", filepath.Join(tempDir, fmtFixture.filename))
-	if actual := ui.OutputWriter.String(); actual != expected {
-		t.Fatalf("got: %q\nexpected: %q", actual, expected)
+	got, err := filepath.Abs(strings.TrimSpace(ui.OutputWriter.String()))
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := filepath.Join(tempDir, fmtFixture.filename)
+
+	if got != want {
+		t.Fatalf("wrong output\ngot:  %s\nwant: %s", got, want)
 	}
 }