tests: example of adding tests using coverage

This tests was AI generated using coverage information.

1. Run all tests `./bin/daslang dastest/dastest.das -- --cov-path c.lcov --test tests/
2. Get summary `./bin/daslang utils/dascov/main.das -- c.lcov --exclude tests`
3. Ask your favorite AI to write tests for uncovered files

Author: aleksisch

tests/linq/test_linq_concat.das

@@ -40,6 +40,11 @@ def test_append(t : T?) {
         append_inplace(a, 5)
         t |> success(a.Equal([0, 1, 2, 3, 4, 5]))
     }
+    t |> run("append from array") @(t : T?) {
+        let arr = [for (x in 0..5); x]
+        var result = append(arr, 5)
+        t |> success(result.Equal([0, 1, 2, 3, 4, 5]))
+    }
 }
 
 [test]
@@ -74,6 +79,11 @@ def test_prepend(t : T?) {
         prepend_inplace(a, -1)
         t |> success(a.Equal([-1, 0, 1, 2, 3, 4]))
     }
+    t |> run("prepend from array") @(t : T?) {
+        let arr = [for (x in 0..5); x]
+        var result = prepend(arr, -1)
+        t |> success(result.Equal([-1, 0, 1, 2, 3, 4]))
+    }
 }
 
 [test]
@@ -108,4 +118,10 @@ def test_concat(t : T?) {
         concat_inplace(a, [for (x in 5..10); x])
         t |> success(a.Equal([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))
     }
+    t |> run("concat from arrays") @(t : T?) {
+        let a = [for (x in 0..5); x]
+        let b = [for (x in 5..10); x]
+        var result = concat(a, b)
+        t |> success(result.Equal([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))
+    }
 }

tests/linq/test_linq_partition.das

@@ -113,6 +113,14 @@ def test_take(t : T?) {
             t |> success(c.a.Equal([i, i * 10]))
         }
     }
+    t |> run("take from array") @(t : T?) {
+        let arr = [for (x in 0..5); x]
+        var result = take(arr, 3)
+        t |> equal(3, length(result))
+        for (c, i in result, 0..3) {
+            t |> equal(c, i)
+        }
+    }
     t |> run("take to array") @(t : T?) {
         var query_array = take_to_array(
             [iterator for(x in 0..5); x],

tests/linq/test_linq_transform.das

@@ -83,6 +83,25 @@ def test_select(t : T?) {
             t |> equal(q._1.a[1], i * 10)
         }
     }
+    t |> run("select from array") @(t : T?) {
+        var nums = [10, 20, 30, 40, 50]
+        var query = select(nums)
+        for (i, q in 0..5, query) {
+            t |> equal(q._0, i)
+            t |> equal(q._1, (i + 1) * 10)
+        }
+    }
+    t |> run("select from array with result selector") @(t : T?) {
+        var nums = [10, 20, 30]
+        var query = _select(
+            nums,
+            (_, _ * 2)
+        )
+        for (i, q in 0..3, query) {
+            t |> equal(q._0, (i + 1) * 10)
+            t |> equal(q._1, (i + 1) * 20)
+        }
+    }
     t |> run("select to sequence") @(t : T?) {
         var chars = ["a", "b", "c", "d", "e"]
         var query = select(chars).to_sequence()