test(library): add basic assertion for env context's tests (#1957)

This PR attempts to better capture the current current incorrect
behavior for `Contexts.env`.

Part of
#1956.

Author: krzema12

.github/workflows/end-to-end-tests.main.kts

@@ -188,7 +188,20 @@ workflow(
                 env = mapOf(
                     FIRST_NAME to "Patrick",
                 ),
-                command = "echo $GREETING $FIRST_NAME",
+                // The assertion below presents the current, undesired behavior related to
+                // env vars, used either from shell or GitHub Actions expressions.
+                // TODO: fix in https://github.com/typesafegithub/github-workflows-kt/issues/1956
+                command = """
+                    cat << EOF > actual
+                    $GREETING-$FIRST_NAME
+                    EOF
+
+                    cat << EOF > expected
+                    -
+                    EOF
+
+                    diff actual expected
+                """.trimIndent(),
             )
             run(
                 name = "Encrypted secret",

.github/workflows/end-to-end-tests.yaml

@@ -99,7 +99,16 @@ jobs:
       name: 'Custom environment variable'
       env:
         $FIRST_NAME: 'Patrick'
-      run: 'echo $GREETING $FIRST_NAME'
+      run: |-
+        cat << EOF > actual
+        $GREETING-$FIRST_NAME
+        EOF
+
+        cat << EOF > expected
+        -
+        EOF
+
+        diff actual expected
     - id: 'step-11'
       name: 'Encrypted secret'
       env: