Add additional info messages for users

Additional messages are needed to better understand the result of the
script. Output codes have been changed to avoid generating interrupts
in cases of normal termination.

.github/workflows/shell.yml

@@ -49,25 +49,39 @@ jobs:
         git config user.email "[email protected]"
         git config user.name "Your Name"
 
-    - name: Test help flags
+    - name: Zero exit code when use help flags
       working-directory: tornado
       run: |
         ../go-mod-bump.sh -h
         ../go-mod-bump.sh -help
 
-    - name: Default exit code must be zero
+    - name: Zero exit code when module name is not set
       working-directory: tornado
       run: |
         ../go-mod-bump.sh
 
-    - name: Test bump '${{ matrix.pkg }}'
+    - name: Update dependencies when there is something to update
       working-directory: tornado
       run: |
-        git checkout --quiet 029fe5d254ab71c1e72444adcda808f5a494084d
+        git checkout --force --quiet 029fe5d254ab71c1e72444adcda808f5a494084d
         ../go-mod-bump.sh ${{ matrix.pkg }}
         commit_count=$(git rev-list --count HEAD ^029fe5d254ab71c1e72444adcda808f5a494084d)
         if [[ "$commit_count" == 0 ]]; then
           echo "ERROR: No changes have been detected, but they must be exist"
           exit 1
         fi
         git diff 029fe5d254ab71c1e72444adcda808f5a494084d
+
+    - name: Zero exit code when nothing to update
+      working-directory: tornado
+      run: |
+        git checkout --force --quiet 029fe5d254ab71c1e72444adcda808f5a494084d
+        ../go-mod-bump.sh ${{ matrix.pkg }}   # update
+        ../go-mod-bump.sh ${{ matrix.pkg }}   # nothing to update
+
+    - name: Zero exit code when no have direct modules
+      run: |
+        mkdir testo
+        cd testo
+        go mod init testo
+        ../go-mod-bump.sh all

go-mod-bump.sh

@@ -91,18 +91,32 @@ fi
 GO_LIST_FORMAT_DIRECT='{{.Path}}{{if .Indirect}}<SKIP>{{end}}{{if .Main}}<SKIP>{{end}}'
 readonly GO_LIST_FORMAT_DIRECT
 
+echoerr "go-mod-bump: fetching direct modules"
+
 # shellcheck disable=SC2068
-DIRECT_MODULES=$(go list -m -f "$GO_LIST_FORMAT_DIRECT" $@ | grep -v '<SKIP>')
+DIRECT_MODULES=$(go list -m -f "$GO_LIST_FORMAT_DIRECT" $@ | grep -v '<SKIP>' || true)
 readonly DIRECT_MODULES
 
+if [ -z "$DIRECT_MODULES" ]; then
+    echoerr "go-mod-bump: nothing to update (no direct modules found)"
+    exit 0
+fi
+
 GO_LIST_FORMAT_FOR_UPDATE='{{.Path}}@{{.Version}}@{{if .Update}}{{.Update.Version}}{{end}}'
 GO_LIST_FORMAT_FOR_UPDATE+='{{if not .Update}}<SKIP>{{end}}' # skip modules without updates.
 readonly GO_LIST_FORMAT_FOR_UPDATE
 
+echoerr "go-mod-bump: fetching latest versions of modules"
+
 # shellcheck disable=SC2086
-MODULES_FOR_UPDATE=$(go list -m -u -f "$GO_LIST_FORMAT_FOR_UPDATE" $DIRECT_MODULES | grep -v '<SKIP>')
+MODULES_FOR_UPDATE=$(go list -m -u -f "$GO_LIST_FORMAT_FOR_UPDATE" $DIRECT_MODULES | grep -v '<SKIP>' || true)
 readonly MODULES_FOR_UPDATE
 
+if [ -z "$MODULES_FOR_UPDATE" ]; then
+    echoerr "go-mod-bump: nothing to update (no new versions found)"
+    exit 0
+fi
+
 function update_module() {
     go get "$1"