var: allow GIT_EDITOR to return null

The handling to die early when there is no EDITOR is valuable when
used in normal code (i.e., editor.c). In git-var, where
null/empty-string is a perfectly valid value to return, it doesn't
make as much sense.

Remove this handling from `git var GIT_EDITOR` so that it does not
fail so noisily when there is no defined editor.

Signed-off-by: Sean Allred <allred.sean@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/var.c

@@ -11,12 +11,7 @@ static const char var_usage[] = "git var (-l | <variable>)";
 
 static const char *editor(int flag)
 {
-	const char *pgm = git_editor();
-
-	if (!pgm && flag & IDENT_STRICT)
-		die("Terminal is dumb, but EDITOR unset");
-
-	return pgm;
+	return git_editor();
 }
 
 static const char *pager(int flag)

t/t0007-git-var.sh

@@ -5,6 +5,12 @@ test_description='basic sanity checks for git var'
 TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
+sane_unset_all_editors () {
+	sane_unset GIT_EDITOR &&
+	sane_unset VISUAL &&
+	sane_unset EDITOR
+}
+
 test_expect_success 'get GIT_AUTHOR_IDENT' '
 	test_tick &&
 	echo "$GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL> $GIT_AUTHOR_DATE" >expect &&
@@ -47,6 +53,62 @@ test_expect_success 'get GIT_DEFAULT_BRANCH with configuration' '
 	)
 '
 
+test_expect_success 'get GIT_EDITOR without configuration' '
+	(
+		sane_unset_all_editors &&
+		test_expect_code 1 git var GIT_EDITOR >out &&
+		test_must_be_empty out
+	)
+'
+
+test_expect_success 'get GIT_EDITOR with configuration' '
+	test_config core.editor foo &&
+	(
+		sane_unset_all_editors &&
+		echo foo >expect &&
+		git var GIT_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_EDITOR with environment variable GIT_EDITOR' '
+	(
+		sane_unset_all_editors &&
+		echo bar >expect &&
+		GIT_EDITOR=bar git var GIT_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_EDITOR with environment variable EDITOR' '
+	(
+		sane_unset_all_editors &&
+		echo bar >expect &&
+		EDITOR=bar git var GIT_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_EDITOR with configuration and environment variable GIT_EDITOR' '
+	test_config core.editor foo &&
+	(
+		sane_unset_all_editors &&
+		echo bar >expect &&
+		GIT_EDITOR=bar git var GIT_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_EDITOR with configuration and environment variable EDITOR' '
+	test_config core.editor foo &&
+	(
+		sane_unset_all_editors &&
+		echo foo >expect &&
+		EDITOR=bar git var GIT_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
 # For git var -l, we check only a representative variable;
 # testing the whole output would make our test too brittle with
 # respect to unrelated changes in the test suite's environment.