added add_mod tests

tests/add_mod_test.rs

@@ -0,0 +1,45 @@
+use std::{collections::HashSet, error::Error, path::PathBuf};
+
+use fomod_manager::{
+    instance::{files_to_install_mod, insert_mod_to_instance},
+    types::{Link, RootConfig},
+};
+
+fn get_parent() -> PathBuf {
+    PathBuf::from(file!()).parent().unwrap().to_owned()
+}
+
+fn load_root() -> RootConfig {
+    RootConfig::load_from_file(get_parent().join("data/root_config_complex.toml")).unwrap()
+}
+
+#[test]
+fn add_simple_mod() -> Result<(), Box<dyn Error>> {
+    let root_config = load_root();
+    let mut instance = root_config.load_instance_by_id("instance_minimal")?;
+    let mod_to_install = root_config.mod_by_id("add_test_1").expect("Mod not found");
+    let files_to_add = files_to_install_mod(&root_config, &instance, &mod_to_install)?;
+
+    insert_mod_to_instance(&mut instance, &mod_to_install, &files_to_add, 0)?;
+
+    let installed_mods = instance.mods();
+
+    assert_eq!(installed_mods.len(), 1);
+
+    let the_mod = installed_mods.first().expect("Asserted before");
+
+    assert_eq!(the_mod.mod_id(), "add_test_1");
+    assert_eq!(the_mod.priority(), 0);
+
+    let expected_files: HashSet<_> = [Link::new("plugin.esp", "Data/plugin.esp")]
+        .into_iter()
+        .collect();
+
+    assert_eq!(
+        *the_mod.files(),
+        expected_files,
+        "Installed files missmatch"
+    );
+
+    Ok(())
+}

tests/data/mods/add_test_1/plugin.esp

@@ -0,0 +1 @@
+plugin.esl-add_test_1