Stop treating fuzz as a special case

We would like to run the build and tests for all crates in the
workspace. In order to do so clear the env vars from the last
loop (setting to the empty string) and check against the empty string
when running specific `cargo` incantations.

ci/run_task.sh

@@ -112,26 +112,23 @@ build_and_test() {
     for crate in "${CRATES[@]}"; do
         local test_vars_script="$REPO_DIR/$crate/contrib/test_vars.sh"
 
-        # Building the fuzz crate is more-or-less just a sanity check.
-        if [ "$crate" = "fuzz" ]; then
-            pushd "$REPO_DIR/$crate" > /dev/null
-            cargo --locked build
-            popd > /dev/null
-            break
-        fi
+        # Clean variables and also make sure they are defined.
+        FEATURES_WITH_STD=""
+        FEATURES_WITH_NO_STD=""
+        FEATURES_WITHOUT_STD=""
+        EXAMPLES=""
 
         verbose_say "Sourcing $test_vars_script"
         if [ -e "$test_vars_script" ]; then
             # Set crate specific variables.
             . "$test_vars_script"
-        else
-            err "Missing $test_vars_script"
-        fi
-        verbose_say "Got vars"
-        verbose_say "FEATURES_WITH_STD: ${FEATURES_WITH_STD:-}"
-        verbose_say "FEATURES_WITHOUT_STD: ${FEATURES_WITHOUT_STD:-}"
-        verbose_say "EXAMPLES: ${EXAMPLES:-}"
 
+            verbose_say "Got test vars:"
+            verbose_say "FEATURES_WITH_STD: ${FEATURES_WITH_STD}"
+            verbose_say "FEATURES_WITH_NO_STD: ${FEATURES_WITH_NO_STD}"
+            verbose_say "FEATURES_WITHOUT_STD: ${FEATURES_WITHOUT_STD}"
+            verbose_say "EXAMPLES: ${EXAMPLES:-}"
+        fi
         pushd "$REPO_DIR/$crate" > /dev/null
 
         do_test
@@ -146,7 +143,7 @@ do_test() {
     $cargo build
     $cargo test
 
-    if [ -n "${EXAMPLES+x}" ]; then
+    if [ -n "${EXAMPLES}" ]; then
         for example in $EXAMPLES; do # EXAMPLES is set in contrib/test_vars.sh
             name="$(echo "$example" | cut -d ':' -f 1)"
             features="$(echo "$example" | cut -d ':' -f 2)"
@@ -164,21 +161,21 @@ do_test() {
 # can be better controlled.
 do_feature_matrix() {
     # rust-miniscript only: https://github.com/rust-bitcoin/rust-miniscript/issues/681
-    if [ -n "${FEATURES_WITH_NO_STD+x}" ]; then
+    if [ -n "${FEATURES_WITH_NO_STD}" ]; then
         $cargo build --no-default-features --features="no-std"
         $cargo test --no-default-features --features="no-std"
 
-        loop_features "no-std" "${FEATURES_WITH_NO_STD:-}"
+        loop_features "no-std" "${FEATURES_WITH_NO_STD}"
     else
         $cargo build --no-default-features
         $cargo test --no-default-features
     fi
 
-    if [ -z "${FEATURES_WITH_STD+x}" ]; then
-        loop_features "std" "${FEATURES_WITH_STD:-}"
+    if [ -n "${FEATURES_WITH_STD}" ]; then
+        loop_features "std" "${FEATURES_WITH_STD}"
     fi
 
-    if [ -z "${FEATURES_WITHOUT_STD+x}" ]; then
+    if [ -n "${FEATURES_WITHOUT_STD}" ]; then
         loop_features "" "$FEATURES_WITHOUT_STD"
     fi
 }