fix default credential builder flags (#526)

Author: polivbr

sdk/identity/examples/default_credentials.rs

@@ -6,7 +6,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     env_logger::init();
 
     let sub_id = std::env::var("AZURE_SUBSCRIPTION_ID")?;
-    let creds = DefaultAzureCredential::default();
+    let creds = DefaultAzureCredentialBuilder::new()
+        .exclude_cli_credential() // disable using CLI for credentials (just as an example)
+        .build();
+
     let res = creds
         .get_token("https://management.azure.com/")
         .await

sdk/identity/src/token_credentials/default_credentials.rs

@@ -3,14 +3,24 @@ use super::{
 };
 use azure_core::TokenResponse;
 
-#[derive(Debug, Default)]
+#[derive(Debug)]
 /// Provides a mechanism of selectively disabling credentials used for a `DefaultAzureCredential` instance
 pub struct DefaultAzureCredentialBuilder {
     include_environment_credential: bool,
     include_managed_identity_credential: bool,
     include_cli_credential: bool,
 }
 
+impl Default for DefaultAzureCredentialBuilder {
+    fn default() -> Self {
+        Self {
+            include_environment_credential: true,
+            include_managed_identity_credential: true,
+            include_cli_credential: true,
+        }
+    }
+}
+
 impl DefaultAzureCredentialBuilder {
     /// Create a new `DefaultAzureCredentialBuilder`
     pub fn new() -> Self {
@@ -168,3 +178,111 @@ fn format_aggregate_error(errors: &[DefaultAzureCredentialError]) -> String {
         .collect::<Vec<String>>()
         .join("\n")
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::matches;
+
+    #[test]
+    fn test_builder_included_credential_flags() {
+        let builder = DefaultAzureCredentialBuilder::new();
+        assert_eq!(builder.include_cli_credential, true);
+        assert_eq!(builder.include_environment_credential, true);
+        assert_eq!(builder.include_managed_identity_credential, true);
+
+        let mut builder = DefaultAzureCredentialBuilder::new();
+        builder.exclude_cli_credential();
+        assert_eq!(builder.include_cli_credential, false);
+        assert_eq!(builder.include_environment_credential, true);
+        assert_eq!(builder.include_managed_identity_credential, true);
+
+        let mut builder = DefaultAzureCredentialBuilder::new();
+        builder.exclude_environment_credential();
+        assert_eq!(builder.include_cli_credential, true);
+        assert_eq!(builder.include_environment_credential, false);
+        assert_eq!(builder.include_managed_identity_credential, true);
+
+        let mut builder = DefaultAzureCredentialBuilder::new();
+        builder.exclude_managed_identity_credential();
+        assert_eq!(builder.include_cli_credential, true);
+        assert_eq!(builder.include_environment_credential, true);
+        assert_eq!(builder.include_managed_identity_credential, false);
+    }
+
+    macro_rules! contains_credential {
+        ($creds:expr, $p:pat) => {
+            $creds.sources.iter().any(|x| matches!(x, $p))
+        };
+    }
+
+    #[test]
+    fn test_credential_sources() {
+        let mut builder = DefaultAzureCredentialBuilder::new();
+
+        // test with all sources
+
+        let credential = builder.build();
+        assert_eq!(credential.sources.len(), 3);
+
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::Environment(_)
+        ));
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::AzureCli(_)
+        ));
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::ManagedIdentity(_)
+        ));
+
+        // remove environment source
+
+        builder.exclude_environment_credential();
+        let credential = builder.build();
+
+        assert_eq!(credential.sources.len(), 2);
+
+        assert!(!contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::Environment(_)
+        ));
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::AzureCli(_)
+        ));
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::ManagedIdentity(_)
+        ));
+
+        // remove cli source
+
+        builder.exclude_cli_credential();
+        let credential = builder.build();
+
+        assert_eq!(credential.sources.len(), 1);
+
+        assert!(!contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::Environment(_)
+        ));
+        assert!(!contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::AzureCli(_)
+        ));
+        assert!(contains_credential!(
+            credential,
+            DefaultAzureCredentialEnum::ManagedIdentity(_)
+        ));
+
+        // remove managed identity source
+
+        builder.exclude_managed_identity_credential();
+        let credential = builder.build();
+
+        assert_eq!(credential.sources.len(), 0);
+    }
+}