feat(slurmdb): add InstancesService

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/slurm/slurmdb_instances_test.go

@@ -0,0 +1,93 @@
+package slurm
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestSlurmdbInstancesService_GetInstances(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurmdb/v0.0.40/instances", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"instances": []}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.SlurmdbInstances.GetInstances(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestSlurmdbInstancesService_GetInstancesWithOptions(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurmdb/v0.0.40/instances", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		q := r.URL.Query()
+		if q.Get("cluster") != "test-cluster" {
+			t.Errorf("expected cluster=test-cluster, got %s", q.Get("cluster"))
+		}
+		if q.Get("extra") != "some-extra" {
+			t.Errorf("expected extra=some-extra, got %s", q.Get("extra"))
+		}
+		if q.Get("instance_id") != "i-12345" {
+			t.Errorf("expected instance_id=i-12345, got %s", q.Get("instance_id"))
+		}
+		if q.Get("instance_type") != "t2.micro" {
+			t.Errorf("expected instance_type=t2.micro, got %s", q.Get("instance_type"))
+		}
+		fmt.Fprint(w, `{"instances": []}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	opts := &GetInstancesOptions{
+		Cluster:      Ptr("test-cluster"),
+		Extra:        Ptr("some-extra"),
+		InstanceID:   Ptr("i-12345"),
+		InstanceType: Ptr("t2.micro"),
+	}
+	resp, _, err := client.SlurmdbInstances.GetInstances(context.Background(), opts)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestSlurmdbInstancesService_GetInstance(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurmdb/v0.0.40/instance", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"instances": []}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.SlurmdbInstances.GetInstance(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestSlurmdbInstancesService_GetInstances_InvalidURL(t *testing.T) {
+	client, _ := NewClient("http://invalid-host-does-not-exist.local", nil)
+	_, _, err := client.SlurmdbInstances.GetInstances(context.Background(), nil)
+	if err == nil {
+		t.Fatal("expected error for invalid URL")
+	}
+}