Add "if let" tests

testing/templates/if-let-else.html

@@ -0,0 +1,7 @@
+{%- if !cond -%}
+    !cond
+{%- else if let Ok(ok) = value -%}
+    {{ ok }}
+{%- else if let Err(err) = value -%}
+    {{ err }}
+{%- endif -%}

testing/templates/if-let-shadowing.html

@@ -0,0 +1 @@
+{% if let Some(text) = text %}{{ text }}{% endif %}

testing/templates/if-let-struct.html

@@ -0,0 +1 @@
+{% if let Digits { one, two, three } = digits %}{{ one }} {{ two }} {{ three }}{% endif %}

testing/templates/if-let.html

@@ -0,0 +1 @@
+{% if let Some(some_text) = text %}{{ some_text }}{% endif %}

testing/tests/if_let.rs

@@ -0,0 +1,109 @@
+use askama::Template;
+
+#[derive(Template)]
+#[template(path = "if-let.html")]
+struct IfLetTemplate {
+    text: Option<&'static str>,
+}
+
+#[test]
+fn test_if_let() {
+    let s = IfLetTemplate {
+        text: Some("hello"),
+    };
+    assert_eq!(s.render().unwrap(), "hello");
+
+    let t = IfLetTemplate { text: None };
+    assert_eq!(t.render().unwrap(), "");
+}
+
+#[derive(Template)]
+#[template(path = "if-let-shadowing.html")]
+struct IfLetShadowingTemplate {
+    text: Option<&'static str>,
+}
+
+#[test]
+fn test_if_let_shadowing() {
+    let s = IfLetShadowingTemplate {
+        text: Some("hello"),
+    };
+    assert_eq!(s.render().unwrap(), "hello");
+
+    let t = IfLetShadowingTemplate { text: None };
+    assert_eq!(t.render().unwrap(), "");
+}
+
+struct Digits {
+    one: i32,
+    two: i32,
+    three: i32,
+}
+
+#[derive(Template)]
+#[template(path = "if-let-struct.html")]
+struct IfLetStruct {
+    digits: Digits,
+}
+
+#[test]
+fn test_if_let_struct() {
+    let digits = Digits {
+        one: 1,
+        two: 2,
+        three: 3,
+    };
+    let s = IfLetStruct { digits };
+    assert_eq!(s.render().unwrap(), "1 2 3");
+}
+
+#[derive(Template)]
+#[template(path = "if-let-struct.html")]
+struct IfLetStructRef<'a> {
+    digits: &'a Digits,
+}
+
+#[test]
+fn test_if_let_struct_ref() {
+    let digits = Digits {
+        one: 1,
+        two: 2,
+        three: 3,
+    };
+    let s = IfLetStructRef { digits: &digits };
+    assert_eq!(s.render().unwrap(), "1 2 3");
+}
+
+#[derive(Template)]
+#[template(path = "if-let-else.html")]
+struct IfLetElse {
+    cond: bool,
+    value: Result<i32, &'static str>,
+}
+
+#[test]
+fn test_if_let_else() {
+    let s = IfLetElse {
+        cond: false,
+        value: Ok(4711),
+    };
+    assert_eq!(s.render().unwrap(), "!cond");
+
+    let s = IfLetElse {
+        cond: true,
+        value: Ok(4711),
+    };
+    assert_eq!(s.render().unwrap(), "4711");
+
+    let s = IfLetElse {
+        cond: false,
+        value: Err("fail"),
+    };
+    assert_eq!(s.render().unwrap(), "!cond");
+
+    let s = IfLetElse {
+        cond: true,
+        value: Err("fail"),
+    };
+    assert_eq!(s.render().unwrap(), "fail");
+}