add no lib targets test (#847)

* Add snapshot testing with `insta`

* temporary dead code allows

* explicitly disable backtraces

* use `insta_cmd` for command snapshots

* move snapshot tests to lib tests

* add snapshot bin test harness

* Revert "move snapshot tests to lib tests"

This reverts commit 72f99bc.

* Add test for no lib targets in the workspace

* move snapshot outputs to lib tests

* move snapshots directory to lib tests

* Revert "move snapshots directory to lib tests"

This reverts commit b56a113.

* Revert "move snapshot outputs to lib tests"

This reverts commit 8b6494c.

* add test files

* Add snapshot testing with `insta`

* temporary dead code allows

* explicitly disable backtraces

* use `insta_cmd` for command snapshots

* move snapshot tests to lib tests

* add snapshot bin test harness

* fix docs

* clippy fixes

* fix merge ;(

* ...

* remove old test file

* unformat Cargo.toml

* clean up

src/snapshot_tests.rs

@@ -128,7 +128,6 @@ impl fmt::Display for CommandResult {
 ///   `test_outputs/snapshot_tests/{test_name}-{"args" | "output"}.snap
 /// - `invocation` is a list of arguments of the command line invocation,
 ///   starting with `["cargo", "semver-checks"]`.
-#[allow(dead_code)] // TODO
 fn assert_integration_test(test_name: &str, invocation: &[&str]) {
     // remove the backtrace environment variable, as this may cause non-
     // reproducible snapshots.
@@ -176,3 +175,23 @@ fn assert_integration_test(test_name: &str, invocation: &[&str]) {
 
     insta::assert_snapshot!(format!("{test_name}-output"), result);
 }
+
+/// [#163](/~https://github.com/obi1kenobi/cargo-semver-checks/issues/163)
+///
+/// Running `cargo semver-checks --workspace` on a workspace that doesn't
+/// have any library targets should be an error.
+#[test]
+fn workspace_no_lib_targets_error() {
+    assert_integration_test(
+        "workspace_no_lib_targets",
+        &[
+            "cargo",
+            "semver-checks",
+            "--manifest-path",
+            "test_crates/manifest_tests/no_lib_targets/new",
+            "--baseline-root",
+            "test_crates/manifest_tests/no_lib_targets/old",
+            "--workspace",
+        ],
+    );
+}

test_crates/manifest_tests/no_lib_targets/new/Cargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+resolver = "2"
+members = ["bin_only"]

test_crates/manifest_tests/no_lib_targets/new/bin_only/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "bin_only"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

test_crates/manifest_tests/no_lib_targets/new/bin_only/src/main.rs

@@ -0,0 +1 @@
+fn main() {}

test_crates/manifest_tests/no_lib_targets/old/Cargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+resolver = "2"
+members = ["bin_only"]

test_crates/manifest_tests/no_lib_targets/old/bin_only/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "bin_only"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

test_crates/manifest_tests/no_lib_targets/old/bin_only/src/main.rs

@@ -0,0 +1 @@
+fn main() {}

test_outputs/snapshot_tests/cargo_semver_checks__snapshot_tests__workspace_no_lib_targets-input.snap

@@ -0,0 +1,30 @@
+---
+source: src/snapshot_tests.rs
+expression: check
+---
+Check(
+  scope: Scope(
+    mode: DenyList(PackageSelection(
+      selection: Workspace,
+      excluded_packages: [],
+    )),
+  ),
+  current: Rustdoc(
+    source: Root("test_crates/manifest_tests/no_lib_targets/new"),
+  ),
+  baseline: Rustdoc(
+    source: Root("test_crates/manifest_tests/no_lib_targets/old"),
+  ),
+  release_type: None,
+  current_feature_config: FeatureConfig(
+    features_group: Heuristic,
+    extra_features: [],
+    is_baseline: false,
+  ),
+  baseline_feature_config: FeatureConfig(
+    features_group: Heuristic,
+    extra_features: [],
+    is_baseline: true,
+  ),
+  build_target: None,
+)

test_outputs/snapshot_tests/cargo_semver_checks__snapshot_tests__workspace_no_lib_targets-output.snap

@@ -0,0 +1,8 @@
+---
+source: src/snapshot_tests.rs
+expression: result
+---
+--- error ---
+no crates with library targets selected, nothing to semver-check
+note: only library targets contain an API surface that can be checked for semver
+note: skipped the following crates since they have no library target: bin_only