Add predefined constants (#2054)

tests/constants.rs

@@ -0,0 +1,45 @@
+use super::*;
+
+#[test]
+fn constants_are_defined() {
+  assert_eval_eq("HEX", "0123456789abcdef");
+}
+
+#[test]
+fn constants_are_defined_in_recipe_bodies() {
+  Test::new()
+    .justfile(
+      "
+        @foo:
+          echo {{HEX}}
+      ",
+    )
+    .stdout("0123456789abcdef\n")
+    .run();
+}
+
+#[test]
+fn constants_are_defined_in_recipe_parameters() {
+  Test::new()
+    .justfile(
+      "
+        @foo hex=HEX:
+          echo {{hex}}
+      ",
+    )
+    .stdout("0123456789abcdef\n")
+    .run();
+}
+
+#[test]
+fn constants_can_be_redefined() {
+  Test::new()
+    .justfile(
+      "
+        HEX := 'foo'
+      ",
+    )
+    .args(["--evaluate", "HEX"])
+    .stdout("foo")
+    .run();
+}

tests/functions.rs

@@ -436,15 +436,6 @@ fn semver_matches() {
     .run();
 }
 
-fn assert_eval_eq(expression: &str, result: &str) {
-  Test::new()
-    .justfile(format!("x := {expression}"))
-    .args(["--evaluate", "x"])
-    .stdout(result)
-    .unindent_stdout(false)
-    .run();
-}
-
 #[test]
 fn trim_end_matches() {
   assert_eval_eq("trim_end_matches('foo', 'o')", "f");

tests/lib.rs

@@ -3,7 +3,7 @@ pub(crate) use {
     assert_stdout::assert_stdout,
     assert_success::assert_success,
     tempdir::tempdir,
-    test::{Output, Test},
+    test::{assert_eval_eq, Output, Test},
   },
   cradle::input::Input,
   executable_path::executable_path,
@@ -46,6 +46,7 @@ mod command;
 mod completions;
 mod conditional;
 mod confirm;
+mod constants;
 mod delimiters;
 mod directories;
 mod dotenv;

tests/test.rs

@@ -312,3 +312,12 @@ fn test_round_trip(tmpdir: &Path) {
 
   assert_eq!(reparsed, dumped, "reparse mismatch");
 }
+
+pub fn assert_eval_eq(expression: &str, result: &str) {
+  Test::new()
+    .justfile(format!("x := {expression}"))
+    .args(["--evaluate", "x"])
+    .stdout(result)
+    .unindent_stdout(false)
+    .run();
+}