Test dotenv_override with new harness

dotenv/tests/integration/api/dotenv_override.rs

@@ -1 +1,83 @@
+use crate::util::*;
+use dotenvy::dotenv_override;
+use dotenvy_test_util::*;
 
+#[test]
+fn no_file_ok() {
+    let testenv = TestEnv::init();
+    test_in_env(&testenv, || {
+        dotenv_override().ok();
+    });
+}
+
+#[test]
+fn no_file_err() {
+    let testenv = TestEnv::init();
+    test_in_env(&testenv, || {
+        let err = dotenv_override().unwrap_err();
+        assert_err_not_found(err);
+    });
+}
+
+#[test]
+fn empty_file_is_ok() {
+    let testenv = TestEnv::init_with_envfile("");
+    test_in_env(&testenv, || {
+        assert!(dotenv_override().is_ok());
+    });
+}
+
+#[test]
+fn one_new_var() {
+    let testenv = TestEnv::init_with_envfile("FOOO=bar");
+    test_in_env(&testenv, || {
+        dotenv_override().unwrap();
+        assert_env_var("FOOO", "bar");
+    });
+}
+
+#[test]
+fn one_old_var() {
+    let mut testenv = TestEnv::init_with_envfile("FOOO=from_file");
+    testenv.add_env_var("FOOO", "from_env");
+    test_in_env(&testenv, || {
+        assert_env_var("FOOO", "from_env");
+        dotenv_override().unwrap();
+        assert_env_var("FOOO", "from_file");
+    });
+}
+
+#[test]
+fn one_old_var_one_new_var() {
+    let vars = [("FOOO", "from_file"), ("BARR", "new")];
+    let envfile = create_custom_envfile(&vars);
+    let mut testenv = TestEnv::init_with_envfile(envfile);
+    testenv.add_env_var("FOOO", "from_env");
+    test_in_env(&testenv, || {
+        assert_env_var_unset("BARR");
+        dotenv_override().unwrap();
+        assert_env_vars(&vars);
+    });
+}
+
+#[test]
+fn substitute_self() {
+    let mut testenv = TestEnv::init_with_envfile("FOOO=$FOOO+1");
+    testenv.add_env_var("FOOO", "test");
+    test_in_env(&testenv, || {
+        assert_env_var("FOOO", "test");
+        dotenv_override().unwrap();
+        assert_env_var("FOOO", "test+1");
+    });
+}
+
+#[test]
+fn substitute_self_twice() {
+    let mut testenv = TestEnv::init_with_envfile("FOOO=$FOOO+1\nFOOO=$FOOO+1");
+    testenv.add_env_var("FOOO", "test");
+    test_in_env(&testenv, || {
+        assert_env_var("FOOO", "test");
+        dotenv_override().unwrap();
+        assert_env_var("FOOO", "test+1+1");
+    });
+}