Issue #379 was fixed

This PR adds the tests by @msrd0 <git@msrd0.de> that failed before.
The error was fixed somewhen between f23162a and now, so these tests
serve to prevent regressions in the future.

I simplified the tests very slightly to omit whitespaces in the output.

testing/templates/macro-import-str-cmp-macro.html

@@ -0,0 +1,13 @@
+{% macro strcmp0(s, other) -%}
+    {%- if s == "foo" -%}
+        foo
+    {%- else if s == other -%}
+        other
+    {%- else -%}
+        neither
+    {%- endif -%}
+{% endmacro %}
+
+{% macro strcmp(s) %}
+    {%- call strcmp0(s, "bar") -%}
+{% endmacro %}

testing/templates/macro-import-str-cmp.html

@@ -0,0 +1,15 @@
+{%- import "macro-import-str-cmp-macro.html" as macros -%}
+
+A
+
+{%- call macros::strcmp("foo") -%}
+
+B
+
+{%- call macros::strcmp("bar") -%}
+
+C
+
+{%- call macros::strcmp("cat") -%}
+
+D

testing/tests/macro.rs

@@ -63,3 +63,13 @@ fn test_nested_macro_with_args() {
     let t = NestedMacroArgsTemplate {};
     assert_eq!(t.render().unwrap(), "first second");
 }
+
+#[derive(Template)]
+#[template(path = "macro-import-str-cmp.html")]
+struct StrCmpTemplate;
+
+#[test]
+fn str_cmp() {
+    let t = StrCmpTemplate;
+    assert_eq!(t.render().unwrap(), "AfooBotherCneitherD");
+}