Propogate size_hint from sub-blocks (#788)

Closes #786

4 files changed, 52 insertions, 0 deletions

diff --git a/testing/templates/size-child-super.txt b/testing/templates/size-child-super.txt
new file mode 100644
index 0000000..77c2916
--- /dev/null
+++ b/testing/templates/size-child-super.txt
@@ -0,0 +1,2 @@
+{% extends "size-parent.txt" %}
+{% block main %}{% call super() %}{% endblock %}
diff --git a/testing/templates/size-child.txt b/testing/templates/size-child.txt
new file mode 100644
index 0000000..86adbf8
--- /dev/null
+++ b/testing/templates/size-child.txt
@@ -0,0 +1,2 @@
+{% extends "size-parent.txt" %}
+{% block main %}{% if true %}123{% endif %}{% endblock %}
diff --git a/testing/templates/size-parent.txt b/testing/templates/size-parent.txt
new file mode 100644
index 0000000..e277a24
--- /dev/null
+++ b/testing/templates/size-parent.txt
@@ -0,0 +1 @@
+{% block main %}{% if true %}12345{% endif %}{% endblock %}
diff --git a/testing/tests/size_hint.rs b/testing/tests/size_hint.rs
new file mode 100644
index 0000000..a9f8428
--- /dev/null
+++ b/testing/tests/size_hint.rs
@@ -0,0 +1,47 @@
+use askama::Template;
+
+macro_rules! test_size {
+    ($source:literal, $expected:expr) => {{
+        #[derive(Template)]
+        #[template(source = $source, ext = "txt")]
+        struct T(bool);
+
+        assert_eq!(T::SIZE_HINT, $expected);
+    }};
+}
+
+#[test]
+fn test_cond_size_hint() {
+    test_size!("{% if self.0 %}12345{% else %}12345{% endif %}", 10);
+}
+
+#[test]
+fn test_match_size_hint() {
+    test_size!(
+        "{% match self.0 %}{% when true %}12345{% else %}12345{% endmatch %}",
+        5
+    );
+}
+
+#[test]
+fn test_loop_size_hint() {
+    test_size!("{% for i in 0..1 %}12345{% endfor %}", 7);
+}
+
+#[test]
+fn test_block_size_hint() {
+    #[derive(Template)]
+    #[template(path = "size-child.txt")]
+    struct T;
+
+    assert_eq!(T::SIZE_HINT, 3);
+}
+
+#[test]
+fn test_super_size_hint() {
+    #[derive(Template)]
+    #[template(path = "size-child-super.txt")]
+    struct T;
+
+    assert_eq!(T::SIZE_HINT, 5);
+}