ref(tests): Decouple test env vars from trycmd code

As a part of #2194, I intend to introduce the [`assert_cmd` crate](https://docs.rs/assert_cmd/latest/assert_cmd/) to have more control over how the assertions for the chunk upload tests are run. This control would be difficult to achieve with `trycmd`.

So, here, I am splitting off the logic for setting environment variables to make it also reusable for `assert_cmd` tests

tests/integration/mod.rs

@@ -17,6 +17,7 @@ mod send_envelope;
 mod send_event;
 mod send_metric;
 mod sourcemaps;
+mod test_utils;
 mod token_validation;
 mod uninstall;
 mod update;
@@ -31,27 +32,28 @@ use std::path::Path;
 use mockito::{self, mock, server_url, Matcher, Mock};
 use trycmd::TestCases;
 
+use test_utils::env;
+
 pub const UTC_DATE_FORMAT: &str = r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{6,9}Z";
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
 pub fn register_test_without_token(path: &str) -> TestCases {
     let test_case = TestCases::new();
-    let server_addr = mockito::server_address();
-    test_case
-        .env("SENTRY_INTEGRATION_TEST", "1")
-        .env("SENTRY_URL", server_url())
-        .env("SENTRY_ORG", "wat-org")
-        .env("SENTRY_PROJECT", "wat-project")
-        .env("SENTRY_DSN", format!("http://test@{}/1337", server_addr))
-        .case(format!("tests/integration/_cases/{path}"));
+
+    env::set(|k, v| {
+        test_case.env(k, v);
+    });
+
+    test_case.case(format!("tests/integration/_cases/{path}"));
     test_case.insert_var("[VERSION]", VERSION).unwrap();
     test_case
 }
 pub fn register_test(path: &str) -> TestCases {
-    let auth_token = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
-
     let test_case = register_test_without_token(path);
-    test_case.env("SENTRY_AUTH_TOKEN", auth_token);
+
+    env::set_auth_token(|k, v| {
+        test_case.env(k, v);
+    });
 
     test_case
 }

tests/integration/test_utils/env.rs

@@ -0,0 +1,25 @@
+//! Utilities for setting environment variables in integration tests.
+
+use std::borrow::Cow;
+
+/// Set the environment variables, which should be set for all integration tests,
+/// using the provided setter function.
+/// The setter function takes as parameters the environment variable name, and the
+/// value to set it to, in that order.
+pub fn set(mut setter: impl FnMut(&'static str, Cow<'static, str>)) {
+    let dsn = format!("http://test@{}/1337", mockito::server_address()).into();
+
+    setter("SENTRY_INTEGRATION_TEST", "1".into());
+    setter("SENTRY_ORG", "wat-org".into());
+    setter("SENTRY_PROJECT", "wat-project".into());
+    setter("SENTRY_URL", mockito::server_url().into());
+    setter("SENTRY_DSN", dsn);
+}
+
+/// Set the auth token environment variable using the provided setter function.
+pub fn set_auth_token(setter: impl FnOnce(&'static str, Cow<'static, str>)) {
+    setter(
+        "SENTRY_AUTH_TOKEN",
+        "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef".into(),
+    );
+}

tests/integration/test_utils/mod.rs

@@ -0,0 +1,3 @@
+//! A collection of utilities for integration tests.
+
+pub mod env;