test(add): Added test case for prefixed v in version

tests/testsuite/cargo_add/mod.rs

@@ -126,6 +126,7 @@ mod path_base_unstable;
 mod path_dev;
 mod path_inferred_name;
 mod path_inferred_name_conflicts_full_feature;
+mod prefixed_v_in_version;
 mod preserve_dep_std_table;
 mod preserve_features_sorted;
 mod preserve_features_table;

tests/testsuite/cargo_add/prefixed_v_in_version/in

@@ -0,0 +1 @@
+../add-basic.in

tests/testsuite/cargo_add/prefixed_v_in_version/mod.rs

@@ -0,0 +1,26 @@
+use cargo_test_support::compare::assert_ui;
+use cargo_test_support::current_dir;
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::str;
+use cargo_test_support::Project;
+
+#[cargo_test]
+fn case() {
+    cargo_test_support::registry::init();
+
+    let project = Project::from_template(current_dir!().join("in"));
+    let project_root = project.root();
+    let cwd = &project_root;
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("add")
+        .arg_line("foo@v0.0.1")
+        .current_dir(cwd)
+        .assert()
+        .code(101)
+        .stdout_eq(str![""])
+        .stderr_eq(file!["stderr.term.svg"]);
+
+    assert_ui().subset_matches(current_dir!().join("out"), &project_root);
+}

tests/testsuite/cargo_add/prefixed_v_in_version/out/Cargo.toml

@@ -0,0 +1,6 @@
+[workspace]
+
+[package]
+name = "cargo-list-test-fixture"
+version = "0.0.0"
+edition = "2015"

tests/testsuite/cargo_add/prefixed_v_in_version/stderr.term.svg

@@ -0,0 +1,33 @@
+<svg width="740px" height="110px" xmlns="http://www.w3.org/2000/svg">
+  <style>
+    .fg { fill: #AAAAAA }
+    .bg { background: #000000 }
+    .fg-red { fill: #AA0000 }
+    .container {
+      padding: 0 10px;
+      line-height: 18px;
+    }
+    .bold { font-weight: bold; }
+    tspan {
+      font: 14px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
+      white-space: pre;
+      line-height: 18px;
+    }
+  </style>
+
+  <rect width="100%" height="100%" y="0" rx="4.5" class="bg" />
+
+  <text xml:space="preserve" class="container fg">
+    <tspan x="10px" y="28px"><tspan class="fg-red bold">error</tspan><tspan class="bold">:</tspan><tspan> invalid version requirement `v0.0.1`</tspan>
+</tspan>
+    <tspan x="10px" y="46px">
+</tspan>
+    <tspan x="10px" y="64px"><tspan>Caused by:</tspan>
+</tspan>
+    <tspan x="10px" y="82px"><tspan>  unexpected character 'v' while parsing major version number</tspan>
+</tspan>
+    <tspan x="10px" y="100px">
+</tspan>
+  </text>
+
+</svg>