fix(spanner): add empty string validation for emulator host

.github/workflows/ci.yml

@@ -26,9 +26,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - os: ubuntu-latest
-            ruby: "2.6"
-            task: "--test"
           - os: ubuntu-latest
             ruby: "2.7"
             task: "--test"
@@ -41,11 +38,14 @@ jobs:
           - os: ubuntu-latest
             ruby: "3.1"
             task: "--test"
+          - os: ubuntu-latest
+            ruby: "3.2"
+            task: "--test"  
           - os: macos-latest
-            ruby: "3.0"
+            ruby: "3.2"
             task: "--test"
           - os: windows-latest
-            ruby: "3.0"
+            ruby: "3.2"
             task: "--test"
       fail-fast: false
     runs-on: ${{ matrix.os }}

google-cloud-spanner/lib/google/cloud/spanner.rb

@@ -96,7 +96,7 @@ def self.new project_id: nil, credentials: nil, scope: nil, timeout: nil,
         project_id    ||= project || default_project_id
         scope         ||= configure.scope
         timeout       ||= configure.timeout
-        emulator_host ||= configure.emulator_host
+        emulator_host = present_or_nil(emulator_host) || present_or_nil(configure.emulator_host)
         endpoint      ||= emulator_host || configure.endpoint
         credentials   ||= keyfile
         lib_name      ||= configure.lib_name
@@ -181,6 +181,13 @@ def self.default_credentials scope: nil
           Google::Cloud.configure.credentials ||
           Spanner::Credentials.default(scope: scope)
       end
+
+      ##
+      # @private checks if string is not nil or empty string
+      # returns the string if present else nil
+      def self.present_or_nil str
+        str.to_s.strip.empty? ? nil : str
+      end
     end
   end
 

google-cloud-spanner/test/google/cloud/spanner_test.rb

@@ -446,6 +446,36 @@ def quota_project_credentials.is_a? target
       end
     end
 
+    it 'ignores emulator_host if empty string' do
+      emulator_host = ""
+      project_id = "arbitrary-string"
+      ENV.stub :[], nil do
+        Google::Cloud::Spanner::Credentials.stub :default, default_credentials do
+          spanner = Google::Cloud::Spanner.new project_id: project_id, emulator_host: emulator_host
+          _(spanner).must_be_kind_of Google::Cloud::Spanner::Project
+          _(spanner.project).must_equal project_id
+          _(spanner.service.host).must_equal "spanner.googleapis.com"
+        end
+      end
+    end
+
+    it "ignores SPANNER_EMULATOR_HOST environment variable if empty" do
+      emulator_host = " "
+      emulator_check = ->(name) { (name == "SPANNER_EMULATOR_HOST") ? emulator_host : nil }
+      # Clear all environment variables, except SPANNER_EMULATOR_HOST
+      ENV.stub :[], emulator_check do
+        # Get project_id from Google Compute Engine
+        Google::Cloud.stub :env, OpenStruct.new(project_id: "project-id") do
+          Google::Cloud::Spanner::Credentials.stub :default, default_credentials do
+            spanner = Google::Cloud::Spanner.new
+            _(spanner).must_be_kind_of Google::Cloud::Spanner::Project
+            _(spanner.project).must_equal "project-id"
+            _(spanner.service.host).must_equal "spanner.googleapis.com"
+          end
+        end
+      end
+    end
+
     it "uses provided lib name and lib version" do
       lib_name = "spanner-ruby"
       lib_version = "1.0.0"