add get_installed test

cmd/tools/vpm/install_test.v

@@ -162,3 +162,49 @@ fn test_install_potentially_conflicting() {
 	manifest = get_vmod('iui')
 	assert manifest.name == 'iui'
 }
+
+fn test_get_installed_version() {
+	test_project_path := os.join_path(test_path, 'test_project')
+	os.mkdir_all(test_project_path)!
+	os.chdir(test_project_path)!
+	os.write_file('v.mod', '')!
+	os.execute_opt('git init && git add . && git commit -m "initial commit"') or {
+		assert false, err.msg()
+		return
+	}
+	mut mod := Module{
+		install_path: test_project_path
+	}
+	mod.get_installed()
+	assert mod.is_installed
+	assert mod.installed_version == ''
+
+	// Create a tag -> latests commit and tag are at the same state,
+	// but it should not be treated as a version installation, when there is another head branch.
+	os.execute_opt('git tag v0.1.0') or {
+		assert false, err.msg()
+		return
+	}
+	mod.is_installed = false
+	mod.get_installed()
+	assert mod.is_installed
+	assert mod.installed_version == ''
+
+	os.execute_opt('git checkout v0.1.0') or {
+		assert false, err.msg()
+		return
+	}
+	mod.is_installed = false
+	mod.get_installed()
+	assert mod.is_installed
+	assert mod.installed_version == ''
+
+	os.execute_opt('git branch -D master && git reset --hard v0.1.0') or {
+		assert false, err.msg()
+		return
+	}
+	mod.is_installed = false
+	mod.get_installed()
+	assert mod.is_installed
+	assert mod.installed_version == 'v0.1.0'
+}

cmd/tools/vpm/parse.v

@@ -152,9 +152,9 @@ fn (mut p Parser) parse_module(m string) {
 	}
 }
 
-// TODO: add unit test
 fn (mut m Module) get_installed() {
 	refs := os.execute_opt('git ls-remote --refs ${m.install_path}') or { return }
+	vpm_log(@FILE_LINE, @FN, 'refs: ${refs}')
 	m.is_installed = true
 	// In case the head just temporarily matches a tag, make sure that there
 	// really is a version installation before adding it as `installed_version`.