1 files changed, 40 insertions, 1 deletions

diff --git a/src/prove.c b/src/prove.c
index 38d6b7c..33757f3 100644
--- a/src/prove.c
+++ b/src/prove.c
@@ -265,7 +265,7 @@ static void TEST_mark_syntax_error()
 
     C_output_from_user_input_is(
         "#mark =bar",
-        "#marker must be non-null.\n",
+        "#marker must be non-empty.\n",
         "#mark - empty error");
 
     C_output_from_user_input_is(
@@ -394,6 +394,42 @@ static void TEST_mark()
         "#mark - all marks deleted");
 }
 
+static void TEST_substitute_syntax_error()
+{
+    C_output_from_user_input_contains(
+        "#substitute = ",
+        "#substitute must be non-empty.",
+        "#substitute - syntax error");
+}
+
+static void TEST_substitute()
+{
+    C_output_from_user_input_contains(
+        "#substitute foo=bar",
+        "#new substitution: foo=bar\n",
+        "#substitute - new substitute is created");
+
+    C_edit_from_user_input_is(
+        "#substitute foo",
+        "#substitute foo=bar",
+        "#substitute - substitute can be edited");
+
+    C_simulated_output_is(
+        "The word foo should be bar",
+        "The word bar should be bar",
+        "#substitute - foo should be bar");
+
+    C_output_from_user_input_is(
+        "#substitute foo=",
+        "#deleting substitution: foo=bar\n",
+        "#substitute - substitute is deleted");
+
+    C_simulated_output_is(
+        "The word foo should not be bar",
+        "The word foo should not be bar",
+        "#substitute - foo should not be bar");
+}
+
 void prove()
 {
     _is_proving = 1;
@@ -405,6 +441,9 @@ void prove()
     do_test(TEST_mark_reset_step2, "#mark reset step 2");
     do_test(TEST_mark, "#mark usage");
 
+    do_test(TEST_substitute_syntax_error, "#substitute syntax error");
+    do_test(TEST_substitute, "#substitute usage");
+
     done_testing();
 
     _is_proving = 0;