add pending mode for test

[summerpro]

From：cosmos/ethermint#571

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md

• Reviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge PR #XYZ: [title]" (coding standards)

[codecov-io]

Codecov Report

Merging #506 (5946b89) into dev (aeb74ad) will decrease coverage by 0.55%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##              dev     #506      +/-   ##
==========================================
- Coverage   67.53%   66.97%   -0.56%     
==========================================
  Files         274      274              
  Lines       16414    16550     +136     
==========================================
  Hits        11085    11085              
- Misses       4711     4847     +136     
  Partials      618      618              

Impacted Files	Coverage Δ
app/rpc/backend/backend.go	0.00% <0.00%> (ø)
app/rpc/namespaces/eth/api.go	0.00% <0.00%> (ø)
app/rpc/types/block.go	0.00% <0.00%> (ø)
app/rpc/types/utils.go	0.00% <0.00%> (ø)

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